Directional regulation and control method for table vinegar production through solid-state fermentation tank and application of directional regulation and control method

Abstract

The invention belongs to the technical field of vinegar brewing, and discloses a directional regulation and control method for vinegar production through a solid-state fermentation tank and application of the directional regulation and control method. The preparation method comprises the following steps: preparing raw materials into mash; adding the wine mash and auxiliary materials into a solid-state fermentation tank, and inoculating an acetic fermentation strain for acetic fermentation; the whole acetic fermentation process is divided into four fermentation stages, the fermentation process is regulated and controlled through dissolved oxygen control in each fermentation stage, when the oxygen-carbon dynamic index reaches a set interval, the dissolved oxygen control in the next fermentation stage is carried out, and fermentation is finished when the ethanol content in the vinegar culture is lower than 0.5 g / 100g and the total acidity is not increased any more. The method provided by the invention is suitable for solid-state fermentation production of vinegar, realizes directional regulation and control of flavor substances of the vinegar, shortens the fermentation period, remarkably improves the flavor of the vinegar, improves the production efficiency, realizes automation and high efficiency of the production process, and has wide application prospects and popularization values.

Description

Technical Field

[0001] The invention belongs to the technical field of vinegar brewing and discloses a directional control method for producing vinegar in a solid-state fermentation tank and application thereof. Background Art

[0002] Vinegar has a long history in my country, and most traditional vinegar brewing companies still use traditional solid-state fermentation technology to produce vinegar. Solid-state fermentation brewing technology is based on the co-fermentation and metabolism of a variety of mixed microorganisms to produce a variety of flavor substances to enrich the sensory flavor of vinegar. Among them, acetoin, in particular, has a pleasant yogurt aroma and creamy taste, which helps to improve the flavor quality of vinegar. In the traditional solid-state fermentation process of vinegar, many key steps, such as fermentation time, ventilation and turning time, and fermentation temperature, are usually controlled by the rich experience of experienced technicians. This experience-driven approach leads to inconsistent quality of fermented products between batches, making it difficult to accurately control the content of important flavor substances. Moreover, over-reliance on experience leads to problems such as insufficient process repeatability and controllability.

[0003] With the continuous advancement of automation technology, modern automated equipment has been gradually introduced into vinegar production, bringing new development opportunities to the traditional vinegar industry. Solid-state fermentation tanks have begun to be used in vinegar fermentation, but current fermentation tanks still primarily serve as a replacement for traditional fermentation equipment. Specific process control parameters are still unclear, and precise adjustment of these parameters is not sufficient to achieve targeted control of the target product. Due to the lack of effective process optimization methods, fermentation efficiency and the final quality of vinegar still need to be improved. In particular, there is significant room for improvement in the regulation of flavor compounds, shortening fermentation time, and maintaining stability during production. Therefore, further breakthroughs in automated control technology and process parameter optimization are needed to improve overall production efficiency and product quality. Summary of the Invention

[0004] To address these shortcomings, the present invention provides a method for targeted regulation of vinegar production in a solid-state fermentation tank and its application. This method divides the acetic acid fermentation process into four stages and precisely controls the dissolved oxygen level in each stage, enabling different microorganisms to fully exert their functions at different stages of fermentation. This method, in turn, targets and regulates the production of flavor compounds, achieving rapid accumulation of acetoin and improving the flavor quality of the vinegar. Furthermore, the method, combined with advanced detection equipment and an automated operating system, enables fully automated operation of vinegar production in a solid-state fermentation tank, further improving fermentation stability and efficiency.

[0005] To achieve the above objectives, the present invention provides the following technical solutions: In a first aspect, the present invention provides a method for directional control of vinegar production in a solid-state fermentation tank, comprising the following steps: S1: making raw materials into mash; S2: mixing the wine mash with auxiliary materials to obtain a fermentation raw material; placing the fermentation raw material into the solid-state fermentation tank, inoculating the acetic acid fermentation strain, stirring evenly, and then performing acetic acid fermentation, and ending the fermentation when the ethanol content in the vinegar mash is lower than 0.5 g / 100 g and the total acidity no longer increases; The acetic acid fermentation process is divided into four fermentation stages. Dissolved oxygen is controlled in each fermentation stage. The proportion of oxygen and carbon dioxide in the solid fermentation tank is monitored in real time during the fermentation process. The formula is analyzed. Obtain oxygen and carbon dynamic index during fermentation A i , when the oxygen-carbon dynamic index A i When the control node setting interval of the next fermentation stage is reached, the dissolved oxygen control is adjusted to enter the next fermentation stage; The analytical formula middle: P Indicates the proportion of oxygen in the environment of the solid-state fermentation tank, O Indicates the real-time proportion of oxygen in the solid-state fermentation tank, C Indicates the real-time proportion of carbon dioxide in the solid-state fermentation tank, and measures the oxygen-carbon dynamic index every 5-15 minutes A， i represents the i-th detection time point, A i represents the oxygen-carbon dynamic index at the i-th detection time point; The four fermentation stages of the acetic acid fermentation process and the control node setting interval of the next fermentation stage include: in the first stage, the internal ventilation ratio of the fermenter is set to 15-16 vvm, stirring is performed once every 8-12 hours, each time for 2-4 minutes, and the stirring speed is 2-3 rpm; when the oxygen-carbon dynamic index is in the range of 1.8-2.2, the fermentation enters the second stage from the first stage; in the second stage, the internal ventilation ratio of the fermenter is set to 15-16 vvm, stirring is performed once every 8-12 hours, each time for 4-6 minutes, and the stirring speed is 2-4 rpm; when the oxygen-carbon dynamic index is in the range of 0.1-0.5, the fermentation enters the third stage from the second stage; in the third stage, the internal ventilation ratio of the fermenter is set to 19-21 vvm, stirring is performed once every 8-12 hours, each time for 9-12 minutes, and the stirring speed is 4-5 rpm; when the oxygen-carbon dynamic index is in the range of 1.3-1.7, the fermentation enters the fourth stage from the third stage; in the fourth stage, the internal ventilation ratio of the fermenter is set to 19-21 vvm, stirring once every 8-12 hours, each time for 8-12 minutes, stirring speed 6-8 rpm, and ending fermentation when the ethanol content is lower than 0.5 g / 100 g vinegar mash and the total acidity no longer increases.

[0006] In the method provided by the present invention, total acidity refers to the total amount of acetic acid and other organic acids during the fermentation process, and can be expressed by the concentration of the main acidic components in the vinegar mash, such as acetic acid (acetic acid).

[0007] During the solid-state fermentation process of vinegar, the oxygen and carbon dioxide content in the fermentation environment plays a key regulatory role in the growth and metabolism of microorganisms. The main microorganisms involved in the acetic acid fermentation stage of vinegar include acetic acid bacteria, lactic acid bacteria, molds and yeasts. Among them, lactic acid bacteria are dominant in the early stage of fermentation and are suitable for growing and producing lactic acid in an anaerobic environment; while acetic acid bacteria are dominant in the middle and late stages of fermentation and require aerobic conditions to convert ethanol into acetic acid. In addition, acetic acid bacteria can also convert lactic acid into pyruvic acid and further synthesize acetoin. In this process, oxygen can significantly promote the formation of acetoin. The present invention divides the acetic acid fermentation process into four stages, and accurately controls the dissolved oxygen in each stage. In the first stage, the rapid growth of fermentation microorganisms and the degradation of raw materials are achieved; in the second stage, the production of non-volatile acids is achieved; in the third stage, the directional regulation of microbial communities is achieved; and in the fourth stage, the directional rapid accumulation of acetoin is achieved. The oxygen and carbon dioxide ratios in the solid-state fermentation tank are monitored in real time, and the oxygen-carbon dynamic index ( A i ).when A i When the preset range is reached, the dissolved oxygen control method is adjusted to enter the next fermentation stage. This precise control method not only meets the dissolved oxygen requirements of different microorganisms at each fermentation stage, but also achieves rapid accumulation of acetoin, significantly improving the flavor quality of vinegar.

[0008] After the start of acetic acid fermentation, the oxygen and carbon dioxide ratios in the fermentation tank are measured once, and the first oxygen-carbon dynamic index is calculated. A 1. After an interval of 5-15 minutes, the oxygen and carbon dioxide ratios in the second fermentation tank are obtained to generate the second oxygen-carbon dynamic index. A 2, and so on, we get A i .

[0009] Preferably, the oxygen-carbon dynamic index is measured every 10 minutes. A .

[0010] 10 minutes after the start of acetic acid fermentation, the oxygen and carbon dioxide ratios in the fermentation tank were measured and the first oxygen-carbon dynamic index was calculated. A 1. After an interval of 10 minutes, that is, at the 20th minute of acetic acid fermentation, the oxygen and carbon dioxide ratios in the second fermentation tank were obtained to generate the second oxygen-carbon dynamic index. A 2, and so on, we get A i .

[0011] Preferably, when | A i - A i-1 |= ΔA >4 indicates that the acetic acid fermentation process has entered an abnormal fermentation state; A i-1 Represents the oxygen-carbon dynamic index at the i-1th time interval.

[0012] ΔA It can be used as a control indicator for acetic acid fermentation process. ΔA Beyond the range of 4, that is, the oxygen-carbon dynamic index before and after A If the difference is greater than 4, it is judged that the fermentation process has entered an abnormal fermentation state. The fermentation tank may have faults such as leakage or ventilation obstruction, and the fermentation tank operation status needs to be checked in time.

[0013] Preferably, in the first stage, the internal ventilation ratio of the fermenter is set to 15-16 vvm, stirring is performed once every 12 hours, each time for 2-4 min, and the stirring speed is 2-3 rpm; in the second stage, the internal ventilation ratio of the fermenter is set to 15-16 vvm, stirring is performed once every 12 hours, each time for 4-6 min, and the stirring speed is 2-4 rpm; in the third stage, the internal ventilation ratio of the fermenter is set to 19-21 vvm, stirring is performed once every 8 hours, each time for 9-12 min, and the stirring speed is 4-5 rpm; in the fourth stage, the internal ventilation ratio of the fermenter is set to 19-21 vvm, stirring is performed once every 8 hours, each time for 8-12 min, and the stirring speed is 6-8 rpm.

[0014] Preferably, in S1, the raw materials are pretreated, liquefied, and saccharified to obtain a fermentation matrix; alcohol fermentation bacteria are introduced into the fermentation matrix, stirred evenly, and then alcohol fermentation is carried out to form mash.

[0015] The raw materials used in the vinegar production method provided by the present invention are grains and their by-products, including but not limited to glutinous rice, rice, sorghum, millet, corn, sweet potato, dried sweet potato, potato and dried potato.

[0016] More preferably, the raw material is sorghum or rice.

[0017] The liquefaction method provided by the present invention comprises grinding the raw material, adding an appropriate amount of water and amylase, and heating and stirring to swell the starch granules and decompose them into soluble sugars. The amylase can be selected based on the characteristics of the raw material and fermentation conditions, including but not limited to high-temperature α-amylase, medium-temperature α-amylase, acid-resistant α-amylase, engineered α-amylase, or complex enzyme preparations.

[0018] More preferably, the liquefaction method comprises adding a thermostable α-amylase to the raw material at a ratio of 900-1000 U / kg, and liquefying the raw material at 75-90° C. for 30-60 min.

[0019] The saccharification method provided herein involves converting the starch in the raw material into fermentable sugars using a saccharifying agent. The type of saccharifying agent, an acid-resistant α-amylase, and the saccharification method can be selected according to actual needs. The saccharifying agent can be selected from one or more combinations of Daqu, Xiaoqu, Fuqu, Hongqu, liquid qu, or amylase preparations.

[0020] More preferably, the saccharification method is to reduce the temperature of the mash to 55-60° C. after the liquefaction is completed, add saccharifying enzyme to the mash at a ratio of 1300-1500 U / kg, and keep the temperature for 1 hour.

[0021] In step 1 of the method provided herein, after pretreatment, liquefaction, and saccharification of the raw materials, the resulting fermentation substrate can be a saccharified liquid or a primary mash. The resulting fermentation substrate can be placed in a fermentation tank or ceramic vat for alcohol fermentation. The fermentation bacteria used in the alcohol fermentation include, but are not limited to, yeasts, molds, and lactic acid bacteria, and can be introduced in the form of Daqu, pure strains of inoculants, or composite inoculants.

[0022] More preferably, Daqu and active dry yeast are added to the fermentation matrix, and water 3.2-3.8 times the weight of the fermentation matrix is added to carry out alcohol fermentation; the fermentation temperature of the alcohol fermentation is 28-32°C, and the fermentation is stopped when the alcohol content of the mash is 7.0%-8.0% (w / w) and the total acid per unit mass is 0.5-1.5 g / 100 g.

[0023] The end point of alcoholic fermentation is when the alcohol content of the mash is 7.0%-8.0% (w / w) and the total acidity per unit mass is 0.5-1.5 g / 100 g. This standard is used to control the duration of alcoholic fermentation. Generally, the end point of fermentation can be reached in 7-9 days.

[0024] The amount of Daqu and active dry yeast added can be adjusted according to the specific fermentation substrate and fermentation process. Active dry yeast can be added directly to the fermentation substrate or first rehydrated and activated before adding to the fermentation substrate.

[0025] More preferably, the mass ratio of the access amount of the Daqu to the fermentation substrate is 0.625-0.7:1, the addition amount of the active dry yeast is 0.2%-0.3% of the fermentation substrate, and water is added in an amount 3.5-3.6 times the weight of the fermentation substrate; the fermentation temperature of the alcoholic fermentation is 28-32°C, and the fermentation is stopped when the alcohol content of the mash is 7.5%-7.8% (w / w) and the total acid per unit mass is 1 g / 100 g.

[0026] The auxiliary materials used in the method for producing vinegar provided by the present invention can be one or more combinations of bran, rice chaff, rice husk or soybean meal.

[0027] Preferably, the auxiliary materials in S2 are bran and rice husk, and the mass ratio of wine mash, bran and rice husk is 5-6:1.1-1.5:0.6-0.9; the fermentation raw materials are loaded into the solid-state fermentation tank according to 1 / 2-2 / 3 of the volume of the solid-state fermentation tank and stirred and mixed.

[0028] The fermentation raw materials are placed in a solid-state fermentation tank and stirred at 1-6 rpm for 20-30 minutes to achieve a uniform mixing state.

[0029] More preferably, the mass ratio of the wine mash, bran and rice husk is 5:1.3:0.8; and the fermentation raw materials are loaded into the solid-state fermentation tank according to 2 / 3 of the volume of the solid-state fermentation tank.

[0030] The acetic acid fermentation bacteria introduced in step 2 of the method provided by the present invention include but are not limited to acetobacillus, lactic acid bacteria and Bacillus, and can be introduced in the form of vinegar mash, Daqu, bran koji, pure strain bacterial agent or composite bacterial agent.

[0031] Preferably, in S3, the mash from the previous batch of acetic acid fermentation is used as the seed mash, which is used as the source of the acetic acid fermentation bacteria, and the seed mash is introduced into the fermentation tank at a mass ratio of 1:5-20 between the seed mash and the fermentation raw material; or in S3, a mixed bran koji containing acetic acid bacteria, lactic acid bacteria and Bacillus is used as the source of the acetic acid fermentation bacteria, and the mixed bran koji is introduced into the fermentation tank at a mass ratio of 1:5-20 between the mixed bran koji and the fermentation raw material.

[0032] More preferably, the mass ratio of acetic acid bacteria gluten, lactic acid bacteria gluten and Bacillus gluten in the mixed gluten is 1:1-10:1-10.

[0033] The preparation method of the mixed bran koji comprises the following steps: preparing acetic acid bacteria bran koji, lactic acid bacteria bran koji and bacillus bran koji respectively, and compounding the acetic acid bacteria bran koji, lactic acid bacteria bran koji and bacillus bran koji in a mass ratio of 1:1-10:1-10 to obtain the mixed bran koji.

[0034] More preferably, the mixed gluten is prepared by compounding acetic acid bacteria gluten, lactic acid bacteria gluten and Bacillus gluten in a mass ratio of 1:1:1.

[0035] More preferably, the Acetobacter, Lactic Acid Bacteria and Bacillus are derived from the acetic acid fermentation stage in vinegar fermentation.

[0036] More preferably, the Acetobacter is Acetobacter pasteurianus.

[0037] More preferably, the Acetobacter pasteurianus is Acetobacter pasteurianus CGMCC No.3089.

[0038] More preferably, the lactic acid bacteria include one or a combination of Lactobacillus helveticus, Lactobacillus fermentum, Lactobacillus plantarum, Lactobacillus acidophilus, Pediococcus acidilactici and Streptococcus lactis.

[0039] When multiple lactic acid bacteria are selected, pure strain gluten can be prepared in equal proportions.

[0040] More preferably, the lactic acid bacteria is Lactobacillus helveticus CICC 22172.

[0041] More preferably, the Bacillus is one or a combination of Bacillus subtilis and Bacillus amyloliquefaciens.

[0042] When multiple Bacillus species are selected, pure strain gluten can be prepared in equal proportions.

[0043] More preferably, the Bacillus is selected from Bacillus amyloliquefaciens CICC 21105.

[0044] The present invention provides a method for preparing a mixed bran koji, comprising the following steps: (1) Add 0.4-0.6 times the weight of bran to the GY sterile culture medium and inoculate 3×10 6 -4×10 6 CFU / g of acetic acid bacteria, mix them evenly and place them in the koji making pool for ventilation fermentation. The fermentation temperature is controlled at 28-32℃, and the koji is turned over every 12 hours. 7 -10 9 CFU / g, end the fermentation and obtain acetic acid bacteria bran koji; (2) Add 0.4-0.6 times the weight of bran to the MRS sterile culture medium and inoculate 4×10 5 -5×10 5 CFU / g of lactic acid bacteria, after being mixed evenly, placed in the koji making pool for ventilation fermentation, the fermentation temperature was controlled at 35-37℃, and the koji was turned over every 12 hours. 7 -10 9 CFU / g, end the fermentation and obtain lactic acid bacteria bran koji; (3) Add 0.4-0.6 times the weight of bran to the LB sterile culture medium and inoculate 3×10 6 -4×10 6 CFU / g of Bacillus, after being mixed evenly, placed in the koji making pool for ventilation fermentation, the fermentation temperature was controlled at 35-37℃, and the koji was turned over every 12 hours. 7 -10 9 CFU / g, the fermentation is terminated and Bacillus bran koji is obtained; (4) The acetic acid bacteria gluten, lactic acid bacteria gluten and Bacillus gluten are compounded in a mass ratio of 1:1-10:1-10 to obtain a mixed gluten.

[0045] In a second aspect, the present invention further provides the use of any of the above-mentioned methods for directional control of vinegar production in a solid-state fermentation tank in directional control of acetoin and / or non-volatile acid in vinegar.

[0046] In a third aspect, the present invention also provides vinegar prepared by the method for directional control of producing vinegar in a solid-state fermentation tank as described above.

[0047] Beneficial effects of the present invention: 1. The present invention monitors the oxygen and carbon dynamic index during the acetic fermentation stage, dividing the acetic fermentation process into stages and controlling dissolved oxygen according to the characteristics of the microorganisms and the production of the target product at each stage. In the initial stage of acetic fermentation, a lower aeration ratio, stirring time, and rotation speed are set to ensure the growth of lactic acid bacteria. In subsequent stages, the aeration ratio, stirring time, and rotation speed are increased to promote the growth and metabolism of acetic acid bacteria and enhance the bacterial community's ability to convert acetoin. This sophisticated control method provides the microorganisms with an optimal growth and metabolic environment, thereby specifically improving the yield and quality of the target product.

[0048] 2. Compared to the non-stage control method, vinegar prepared using sorghum and rice as raw materials using the methods provided by the present invention increased acetic acid content in the mash by 23.64%-31.29%, acetoin content by 80%-90.47%, and amino acid nitrogen content by 76.92%. The ratio of volatile and non-volatile acids was also adjusted, resulting in a milder vinegar odor and a longer aftertaste, improving the flavor of the vinegar. The entire acetic acid fermentation cycle was shortened by 2-6 days, raw material utilization increased by 23.50%-28.28%, and the acetic acid fermentation rate was increased, significantly improving fermentation efficiency and accelerating acetic acid accumulation, while saving time and costs for industrial production.

[0049] 3. The method provided by the present invention determines whether to enter the next stage by setting a specific oxygen-carbon dynamic index range for the acetic acid fermentation stage, reducing human interference and making the entire acetic acid fermentation process more accurate and efficient. In combination with solid-state fermentation detection equipment and operating systems, it can realize automated control of the vinegar fermentation process, and has broad application prospects and promotion value. DETAILED DESCRIPTION

[0050] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0051] The word “about” in the embodiments should be understood as the normal fluctuation range that may exist in actual operation, but such fluctuation will not deviate from the essence of the invention or affect the implementation of its technical solution.

[0052] Unless otherwise specified, the percentage sign "%" in the examples refers to the mass percentage of solids, the percentage of solutions refers to the grams of solute contained in 100 mL, and the percentage of liquids refers to the volume ratio of the solutions at 25°C.

[0053] The unit of ventilation ratio in the present invention is vvm: it refers to the ratio of the ventilation volume per minute to the actual volume of the feed liquid in the fermentation tank, that is, the ratio of the gas volume passing through the fermentation tank to the volume of the fermentation liquid per unit time, wherein the gas volume is measured in standard conditions, and its unit is cubic meter / (cubic meter×per minute).

[0054] The test materials used in the present invention are all common commercial products and can be purchased in the market.

[0055] The strains used in the examples of the present invention are: Acetobacter pasteurianus ( Acetobacter pasteurianus ) CGMCC No.3089, provided by China Microorganism Culture Collection Center (CGMCC), which has been used in “The Evolutionary Response of AlcoholDehydrogenase and Aldehyde Dehydrogenases of Acetobacter pasteurianus CGMCC3089 to Ethanol Adaptation” (Yu Zheng et al. Food Sci. Biotechnol. 24(1): 133-140(2015)).

[0056] Lactobacillus helveticus ( Lactobacillus helveticus ) CICC 22172 and Bacillus amyloliquefaciens ( Bacillus amyloliquefaciens ) CICC 21105, provided by China Industrial Microbiological Culture Collection Center.

[0057] The culture medium used in the embodiments of the present invention is: MRS medium (w / v): glucose 2%, casein 1%, beef powder 0.8%, yeast powder 0.5%, anhydrous sodium acetate 0.5%, triammonium citrate 0.2%, dipotassium hydrogen phosphate 0.2%, cysteine hydrochloride 0.05%, magnesium sulfate 0.02%, manganese sulfate 0.005%, Tween 80 0.1%, and the rest is water. The pH was adjusted to 5.2.

[0058] GY medium (w / v): glucose 2%, yeast extract 2%, ethanol 3.5% (v / v), and the rest water.

[0059] LB medium (w / v): peptone 1%, yeast extract 0.5%, NaCl 1%, and the rest water.

[0060] The determination method involved in the embodiments of the present invention is: The determination method of amino acid nitrogen is based on GB 5009.235-2016 National Food Safety Standard - Determination of Amino Acid Nitrogen in Foods; the determination method of lactic acid is based on GB 5009.235-2016 National Food Safety Standard - Determination of Organic Acids in Foods; the determination method of reducing sugar is based on GB 5009.7-2016 National Food Safety Standard - Determination of Reducing Sugar in Foods; the determination method of acetoin is based on QB / T 4234-2011 3-Hydroxy-2-butanone (Acetoin); the determination method of acetic acid is based on GB / T 5009.41-2003 Hygienic Standard for Vinegar - Method of Analysis Example 1 This embodiment provides a method for directional regulation of acetoin and non-volatile acid in the production of traditional vinegar using a drum-type solid-state fermentation tank.

[0061] (1) Raw material pretreatment, liquefaction, and saccharification: After sorghum was crushed, high-temperature resistant α-amylase was added at a ratio of 1000 U / kg, and the mixture was kept warm at 88-90°C for 30 min. After liquefaction, a mash was obtained. When the temperature of the mash dropped to 60°C, saccharifying enzyme was added at a ratio of 1500 U / kg, and the mixture was kept warm at 60°C for 1 h to obtain a saccharified liquid.

[0062] (2) Preparation of wine mash: Place the saccharification liquid in a fermentation tank, add Daqu at a mass ratio of 1:0.625, add 0.2% active dry yeast, add 3.6 times the weight of water as the raw material, control the temperature at 28-30℃ and ferment for 8 days. The alcohol content at the end of fermentation is about 7.5% (w / w), and the total acid per unit mass is about 1g / 100g, thus obtaining wine mash.

[0063] (3) Preparation of mixed bran: Weigh the bran and add GY sterile culture medium at 0.6 times the weight of the bran, then inoculate Acetobacter pasteurianus CGMCC 3089 at an inoculum size of 4×10 6 CFU / g, and after mixing evenly, the mixture was placed in a koji making tank and fermented at 28-32℃, turning the koji every 12 hours, and the fermentation time was 2 days to obtain pure strain of Acetobacter pasteurianus CGMCC3089 bran koji, which contained 10 viable Acetobacter pasteurianus per unit mass. 7 CFU / g.

[0064] Weigh the bran and add MRS sterile medium according to 0.6 times the weight of the bran, and then inoculate Lactobacillus helveticus CICC 22172 at an inoculum size of 5×10 5 CFU / g, and after being mixed evenly, the mixture was placed in a koji making tank and fermented at 35-37℃, with the koji turned over every 12 hours for 2 days to obtain pure strain of Lactobacillus helveticus CICC 22172. The number of viable Lactobacillus helveticus per unit mass in the koji was 10 7 CFU / g.

[0065] Weigh the bran and add LB sterile medium according to 0.6 times the weight of the bran, and inoculate Bacillus amyloliquefaciens CICC 21105 at an inoculum size of 3×10 6 CFU / g, and after being mixed evenly, the mixture was placed in a koji making tank and fermented at 35-37 ° C. The koji was turned over every 12 hours for 2 days to obtain a pure strain of Bacillus amyloliquefaciens CICC21105. The number of viable Bacillus amyloliquefaciens bacteria per unit mass in the koji was 10 7 CFU / g.

[0066] The prepared Acetobacter pasteurianus CGMCC 3089 pure strain bran koji, Lactobacillus helveticus CICC 22172 pure strain bran koji and Bacillus amyloliquefaciens CICC 21105 pure strain bran koji were compounded in a mass ratio of 1:1:1 to obtain a mixed bran koji.

[0067] (4) Four-stage acetic acid fermentation: Add bran and rice husk as two auxiliary materials to the wine mash obtained in step 2, and mix to obtain fermentation raw materials. The mass ratio of wine mash, bran and rice husk in the fermentation raw materials is 5:1.3:0.8. The fermentation raw materials are loaded into a solid fermentation tank, and the filling amount accounts for about 2 / 3 of the volume of the solid fermentation tank. Stir at 4 rpm for 30 min; add the mixed bran koji obtained in step 3 to the solid fermentation tank at a mass ratio of 1:10 to the fermentation raw materials. Continue stirring for 30 min, then stop stirring and start the four-stage acetic acid fermentation. During the fermentation process, the percentage of oxygen in the solid fermentation tank was monitored ( O i ) and the percentage of carbon dioxide ( C i ), record every 5 minutes, according to the formula The oxygen-carbon dynamic index during the solid-state fermentation process was obtained. A i Determine whether the control node of the next stage has been reached, and control the ventilation ratio and stirring parameters of each stage. The setting ranges of the ventilation ratio and stirring parameters of each stage in the four stages and the oxygen and carbon dynamic index of the stage control node are shown in Table 1.

[0068] Table 1

[0069] Fermentation was continued under these conditions, with sampling taking place until the alcohol content of the fermentation medium fell below 0.5 g / 100 g of the fermented mash and the acetic acid concentration remained unchanged. Fermentation was then stopped to obtain the mash. After acetic fermentation, the mash samples were assayed for volatile acid (acetic acid), non-volatile acid (lactic acid), reducing sugars, amino acids (amino acid nitrogen), and the main flavor compound (acetoin). The raw material utilization rate and acetic fermentation rate were calculated. The results are shown in Table 2.

[0070] Comparative Example 1 This comparative example provides a method for producing traditional vinegar using a drum-type solid-state fermentation tank. Unlike Example 1, step 4 utilizes a non-stage control method for the acetic acid fermentation process. During the acetic acid fermentation process, aeration and stirring are performed once every 8 hours for 5 minutes at a rotation speed of 5 rpm and an aeration ratio of 15 v / vm. Under these conditions, fermentation and follow-up sampling are performed until the alcohol content of the fermentation medium falls below 0.5 g / 100 g of the fermented mash and the acetic acid concentration remains unchanged. Fermentation is then terminated to produce the fermented mash. After the acetic acid fermentation is completed, the contents of volatile acid (acetic acid), non-volatile acid (lactic acid), reducing sugars, amino acids (amino acid nitrogen), and the main flavor substance (acetoin) in the resulting fermented mash sample are measured. The raw material utilization rate and acetic acid fermentation rate are calculated. The results are shown in Table 2.

[0071] Table 2 Physical and chemical results of mash samples obtained by different control methods at different acetic acid fermentation stages

[0072] As shown in Table 2, compared with the fermentation method provided in Comparative Example 1, the vinegar produced according to the phased directional control method provided in Example 1 increased the acetic acid content in the vinegar culture by 23.64% and the lactic acid content by 43.26%. The ratio between the two decreased from 2.38 to 2.05, significantly improving the taste of the vinegar, reducing the irritation of the vinegar, and making the aftertaste mellow. The amino acid nitrogen content increased by 76.92%, indicating that the improvement in protein decomposition efficiency helps to enhance the umami and rich taste of the vinegar. The content of acetoin, the main flavor substance in the vinegar mash, increased significantly by 90.47%. Acetoin is an important flavor substance in vinegar. Its significant increase not only enhances the aromatic characteristics of vinegar, but also enriches the overall flavor of vinegar. The fermentation period was shortened by about 6 days, the raw material utilization rate increased by 23.50%, and the acetic acid fermentation rate increased by 75.00%, significantly improving the fermentation efficiency and accelerating the accumulation of acetic acid.

[0073] Example 2 This embodiment provides a method for directional regulation of acetoin and non-volatile acid in the production of rice vinegar using a drum-type solid-state fermentation tank.

[0074] (1) Raw material pretreatment, liquefaction, and saccharification: After the rice is crushed, high-temperature resistant α-amylase is added at a ratio of 900 U / kg, and the mixture is kept warm at 75-85°C for 60 min. After liquefaction, a mash is obtained. When the temperature of the mash drops to 55°C, saccharifying enzyme is added at a ratio of 1300 U / kg, and the mixture is kept warm at 55°C for 1 h to obtain the saccharified raw material.

[0075] (2) Making mash: Place the saccharified raw materials in a fermentation tank, add Daqu and 0.3% active dry yeast in a ratio of 1:0.7, add 3.5 times the weight of water of the raw materials, control the temperature at 28-32℃ and ferment for 6 days. The alcohol content at the end of fermentation is about 7.8% (w / w), and the total acid per unit mass is about 1g / 100g, to obtain mash.

[0076] (3) Preparation of seed mash: Select the vinegar mash from the previous batch of fermentation as the seed mash.

[0077] (4) Four-stage acetic acid fermentation: Add bran and rice husks to the wine mash obtained in step 2 to obtain a fermentation raw material. The mass ratio of wine mash, bran and rice husk in the fermentation raw material is 5:1.1:0.6. The fermentation raw material is placed in a solid fermentation tank with the filling amount accounting for about 2 / 3 of the volume of the fermentation tank. Stir at 4 rpm for 30 min. Add the seed mash obtained in step 3 to the fermentation tank at a mass ratio of mixed bran and fermentation raw material of 1:10. Continue stirring for 30 min, then stop stirring and start the four-stage acetic acid fermentation. During the fermentation process, the percentage of oxygen in the solid fermentation tank was monitored ( O i ) and the percentage of carbon dioxide ( C i ), recorded every 10 minutes, according to the formula The ratio of oxygen and carbon dioxide in the solid-state fermentation tank acetic acid fermentation process was obtained. A i Determine whether the control node for the next stage has been reached, and perform ventilation ratio and stirring control for each stage. The setting ranges for ventilation ratio and stirring parameters for each of the four stages, as well as the oxygen and carbon dynamic index for the stage control node, are shown in Table 3.

[0078] Table 3

[0079] Fermentation was continued under these conditions, with sampling taking place until the alcohol content of the fermentation medium fell below 0.5 g / 100 g of the fermented mash and the acetic acid concentration remained unchanged. Fermentation was then stopped to obtain the mash. After acetic fermentation, the mash samples were assayed for volatile acid (acetic acid), non-volatile acid (lactic acid), reducing sugars, amino acids (amino acid nitrogen), and the main flavor compound (acetoin). Raw material utilization and acetic fermentation rate were calculated. The results are shown in Table 4.

[0080] Comparative Example 2 This comparative example provides a method for producing rice vinegar using a drum-type solid-state fermentation tank. Unlike Example 2, step 4 utilizes a non-stage control method for the acetic acid fermentation process. During the acetic acid fermentation process, aeration and stirring are performed once every 8 hours for 5 minutes at a rotation speed of 5 rpm and an aeration ratio of 15 v / vm. Under these conditions, fermentation and follow-up sampling are performed until the alcohol content of the fermentation medium is less than 0.5 g / 100 g of the fermented mash and the acetic acid concentration remains unchanged. Fermentation is then terminated to produce the fermented mash. After the acetic acid fermentation is completed, the contents of volatile acid (acetic acid), non-volatile acid (lactic acid), reducing sugars, amino acids (amino acid nitrogen), and the main flavor substance (acetoin) in the resulting fermented mash sample are measured, and the raw material utilization rate and acetic acid fermentation rate are calculated. The results are shown in Table 4.

[0081] Table 4 Physical and chemical results of mash samples obtained by different control methods at different acetic acid fermentation stages

[0082] As can be seen from Table 4, compared with the fermentation method provided in Comparative Example 2, the rice vinegar produced according to the staged directional control method provided in Example 2 has an acetic acid content in the vinegar culture increased by 31.29%, a lactic acid content increased by 23.4%, and an amino acid nitrogen content increased by 42.86%. The content of acetoin, the main flavor substance in the vinegar mash, is significantly increased by 80%, the fermentation cycle is shortened by 1-2 days, and the raw material utilization rate is increased by 28.28%.

[0083] In summary, the method provided by the present invention can significantly increase the content of key substances such as acetic acid, lactic acid, reducing sugars and amino acid nitrogen in vinegar, rapidly increase the accumulation of acetoin, improve the ratio of volatile acid to non-volatile acid, make the vinegar odor softer and the aftertaste longer, and improve the flavor of vinegar. This not only improves the flavor quality of vinegar and improves the taste, but also significantly improves production efficiency and economic benefits.

[0084] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for directional control of vinegar production in a solid-state fermentation tank, characterized in that: The following steps are involved: S1: making raw materials into mash; S2: mixing the wine mash with auxiliary materials to obtain a fermentation raw material; placing the fermentation raw material into the solid-state fermentation tank, inoculating the acetic acid fermentation strain, stirring evenly, and then performing acetic acid fermentation, and ending the fermentation when the ethanol content in the vinegar mash is lower than 0.5 g / 100 g and the total acidity no longer increases; The acetic acid fermentation process is divided into four fermentation stages. Dissolved oxygen is controlled in each fermentation stage. The proportion of oxygen and carbon dioxide in the solid fermentation tank is monitored in real time during the fermentation process. The formula is analyzed. Obtain oxygen and carbon dynamic index during fermentation A i , when the oxygen-carbon dynamic index A i When the set interval of the control node of the next fermentation stage is reached, the dissolved oxygen control of the next fermentation stage is carried out; The analytical formula middle: P Indicates the proportion of oxygen in the environment of the solid-state fermentation tank, O Indicates the real-time proportion of oxygen in the solid-state fermentation tank, C Indicates the real-time proportion of carbon dioxide in the solid-state fermentation tank, and measures the oxygen-carbon dynamic index every 5-15 minutes A， i represents the i-th detection time point, A i represents the oxygen-carbon dynamic index at the i-th detection time point; The four fermentation stages of the acetic acid fermentation process and the control node setting interval of the next fermentation stage include: in the first stage, the internal ventilation ratio of the fermenter is set to 15-16 vvm, stirring is performed once every 8-12 hours, each time for 2-4 minutes, and the stirring speed is 2-3 rpm; when the oxygen-carbon dynamic index is in the range of 1.8-2.2, the fermentation enters the second stage from the first stage; in the second stage, the internal ventilation ratio of the fermenter is set to 15-16 vvm, stirring is performed once every 8-12 hours, each time for 4-6 minutes, and the stirring speed is 2-4 rpm; when the oxygen-carbon dynamic index is in the range of 0.1-0.5, the fermentation enters the third stage from the second stage; in the third stage, the internal ventilation ratio of the fermenter is set to 19-21 vvm, stirring is performed once every 8-12 hours, each time for 9-12 minutes, and the stirring speed is 4-5 rpm; when the oxygen-carbon dynamic index is in the range of 1.3-1.7, the fermentation enters the fourth stage from the third stage; in the fourth stage, the internal ventilation ratio of the fermenter is set to 19-21 vvm, stirring once every 8-12 hours, each time for 8-12 minutes, stirring speed 6-8 rpm, and ending fermentation when the ethanol content in the vinegar mash is lower than 0.5 g / 100 g vinegar mash and the total acidity no longer increases.

2. The method for directional control of producing vinegar in a solid-state fermentation tank according to claim 1, wherein: The oxygen-carbon dynamic index is measured every 10 minutes. A .

3. The method for directional control of producing vinegar in a solid-state fermentation tank according to claim 1, wherein: When | A i - A i-1 |= Δ A >4 indicates that the acetic acid fermentation process has entered an abnormal fermentation state; A i-1 Represents the oxygen-carbon dynamic index at the i-1th time interval.

4. The method for directional control of producing vinegar in a solid-state fermentation tank according to claim 1, wherein: In the first stage, the fermentation tank is set to have an internal ventilation ratio of 15-16 vvm, stirring once every 12 hours, each time for 2-4 minutes, and a stirring speed of 2-3 rpm; in the second stage, the fermentation tank is set to have an internal ventilation ratio of 15-16 vvm, stirring once every 12 hours, each time for 4-6 minutes, and a stirring speed of 2-4 rpm; in the third stage, the fermentation tank is set to have an internal ventilation ratio of 19-21 vvm, stirring once every 8 hours, each time for 9-12 minutes, and a stirring speed of 4-5 rpm; in the fourth stage, the fermentation tank is set to have an internal ventilation ratio of 19-21 vvm, stirring once every 8 hours, each time for 8-12 minutes, and a stirring speed of 6-8 rpm.

5. The method for directional control of producing vinegar in a solid-state fermentation tank according to claim 1, wherein: In S1, the raw materials are pretreated, liquefied, and saccharified to obtain a fermentation matrix; alcohol fermentation bacteria are introduced into the fermentation matrix, stirred evenly, and then alcohol fermentation is carried out to form a wine mash.

6. The method for directional control of producing vinegar in a solid-state fermentation tank according to claim 5, wherein: The raw material is sorghum or rice; and / or The liquefaction method comprises adding a thermostable α-amylase to the raw material at a ratio of 900-1000 U / kg, and liquefying at 75-90° C. for 30-60 minutes; and / or The saccharification method comprises: after the liquefaction is completed, the temperature of the mash is lowered to 55-60° C., saccharifying enzyme is added to the mash at a ratio of 1300-1500 U / kg, and the temperature is kept for 1 hour; and / or Daqu and active dry yeast are added to the fermentation matrix, and water is added in an amount 3.2-3.8 times the weight of the fermentation matrix to carry out alcohol fermentation; the fermentation temperature of the alcohol fermentation is 28-32° C., and the fermentation is stopped when the alcohol content of the mash in the solid-state fermentation tank reaches 7.0%-8.0% (w / w) and the total acid per unit mass is 0.5-1.5 g / 100 g.

7. The method for directional control of producing vinegar in a solid-state fermentation tank according to claim 1, wherein: The auxiliary materials in S2 are bran and rice husk, and the mass ratio of the wine mash, bran and rice husk is 5-6:1.1-1.5:0.6-0.9; the fermentation raw materials are loaded into the solid-state fermentation tank according to 1 / 2-2 / 3 of the volume of the solid-state fermentation tank and stirred and mixed.

8. The method for directional control of producing vinegar in a solid-state fermentation tank according to claim 1, wherein: In S2, the mash from the previous batch of acetic acid fermentation is used as the seed mash, which is used as the source of the acetic acid fermentation bacteria, and the seed mash is introduced into the solid-state fermentation tank at a mass ratio of 1:5-20 between the seed mash and the fermentation raw material; or in S2, a mixed bran koji containing acetic acid bacteria, lactic acid bacteria and Bacillus is used as the source of the acetic acid fermentation bacteria, and the mixed bran koji is introduced into the solid-state fermentation tank at a mass ratio of 1:5-20 between the mixed bran koji and the fermentation raw material.

9. Application of the method for directional control of vinegar production in a solid-state fermentation tank according to any one of claims 1 to 8 in directional control of acetoin and / or non-volatile acid in vinegar.

10. Vinegar prepared by the method for directional regulation of vinegar production in a solid-state fermentation tank according to any one of claims 1 to 8.

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