Hawthorn vinegar fermentation method

Abstract

The invention discloses a hawthorn vinegar fermentation method, and relates to the technical field of fruit vinegar fermentation. In the hawthorn wine fermentation stage, grape wine yeast activation liquid is inoculated for fermentation, the high-acidity environment can be tolerated, and the fermented hawthorn wine with the alcohol content meeting the requirement can be obtained; a mixture of original hawthorn vinegar and concentrated hawthorn juice is added in the hawthorn vinegar fermentation stage, the calculation mode of the addition amount is that the acidity of a substrate is improved by 0.3-0.5 g / 100 mL, a mixed carbon source is provided for acetic acid bacteria, the activity of the strain is improved, the adaptation period is shortened, compared with a traditional strain, the independently-bred new strain is better in acid production performance, the alcohol conversion capacity of the new strain under the same substrate is higher, and the production cost is reduced. The fermented hawthorn has higher acetic acid degree and can be applied to fermentation of hawthorn vinegar of 20 t or above in an expanding culture manner, so that the production efficiency is greatly improved. According to the fermentation method, the hawthorn vinegar can be prepared under the condition that an acidity regulator is not additionally added, functional components of the hawthorn are reserved to a greater extent, and the acidity of the original hawthorn vinegar can also be improved.

Description

Technical Field

[0001] The invention relates to the technical field of fruit vinegar fermentation, in particular to a hawthorn vinegar fermentation method. Background Art

[0002] Hawthorn is rich in flavonoids and organic acids, and has been widely developed and applied by food companies in recent years. Hawthorn fruit has a distinct sour taste and a bad taste, which affects the sales of hawthorn and its products. Developing hawthorn vinegar can make up for the defects caused by the sour taste. At present, the main fermentation technologies for hawthorn vinegar include alcohol extraction-liquid-first solid fermentation method, solid-solid fermentation method, etc. The extracted hawthorn wine has a sharp and irritating flavor and loses a lot of nutrients; the solid-solid fermentation hawthorn wine has a long fermentation time and the stability of the original vinegar flavor is difficult to control; the hawthorn original vinegar fermented by two liquid deep fermentation technologies can accumulate flavor substances through microbial metabolism while retaining a clean, refreshing and soft taste, which is especially suitable for the preparation of fruit vinegar beverages, so that the hawthorn vinegar beverage has a rich fruity aroma and a clean and refreshing flavor.

[0003] The polyphenols contained in hawthorn, such as tannins, can have adverse effects on the activity of yeast and acetic acid bacteria. On the other hand, a high acidity environment is also a major stress factor for the reproduction and growth of yeast and acetic acid bacteria. Existing hawthorn acetic acid fermentation technologies mostly use hawthorn vinegar fermentation substrates to add acidity regulators to adjust the pH to make acetic acid fermentation smoother. Before hawthorn vinegar fermentation, a certain concentration of NaOH solution is used to adjust the pH of the fermentation substrate. However, this production process will lose the functional components of hawthorn; other highly acidic fruit juices often use sugar and acid adjustment treatments in the alcohol fermentation process to adapt to the reproduction and fermentation of brewing yeast, which will cause the loss of hawthorn functional components.

[0004] Therefore, it is of great significance to develop a fermentation process that does not require the addition of acidity regulators and can achieve large-scale production of hawthorn vinegar. Among them, the selection of fermentation strains and supporting processes are particularly critical.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The object of the present invention is to provide a hawthorn vinegar fermentation method, aiming to prepare hawthorn vinegar without adding an additional acidity regulator, while improving the acidity of the fermented hawthorn vinegar.

[0007] The present invention is achieved in that:

[0008] In a first aspect, the present invention provides a hawthorn vinegar fermentation method, comprising: hawthorn wine fermentation and hawthorn vinegar fermentation;

[0009] The process of hawthorn wine fermentation includes: mixing concentrated hawthorn juice, water and wine-based sugar source, inoculating wine yeast activation liquid for fermentation, and obtaining hawthorn original wine;

[0010] The process of hawthorn vinegar fermentation includes: preparing a mixture of hawthorn wine, water, hawthorn vinegar and concentrated hawthorn juice into a substrate, carrying out acetic acid bacteria expansion and acetic acid fermentation; acetic acid fermentation is to mix the fermentation liquid after acetic acid bacteria expansion with the substrate for fermentation;

[0011] When preparing the substrate, the amount of the mixture of hawthorn vinegar and concentrated hawthorn juice added is adjusted, and the total acid is calculated as acetic acid, so that the acidity of the substrate is increased by 0.3g / 100mL-0.5g / 100mL.

[0012] In an optional embodiment, in the acetic acid fermentation process, the acetic acid bacteria used is 83448-6b-1, which is screened from the thermostable acetic acid bacteria CGMCC No.8189, and the screening steps are as follows:

[0013] The thermostable acetic acid bacteria CGMCC No.8189 was inoculated into hawthorn wine for cultivation. When the acidity increased to 2.0g / 100mL, the culture was continued for multiple times. The fermentation liquid was diluted into different concentrations for coating and separation. The strains with large transparent circles and good colony growth were selected for preservation. The strains screened initially were rescreened to select the strains with the best acetic acid production performance.

[0014] Preferably, the process of fermenting hawthorn vinegar comprises: culturing the substrate and acetic acid bacteria in a seed expansion tank, and then entering a primary expansion tank for mixed culture with the substrate, the expansion liquid obtained in the primary expansion tank is divided into two parts, the first part returns to the seed expansion tank for acetic acid bacteria back-inoculation and subculture, and the second part is divided into the following two situations: when the acetic acid bacteria generation is 0, the second part enters the first fermentation tank for acetic acid fermentation; when the acetic acid bacteria generation is greater than or equal to 1, the second part enters the secondary expansion tank for expansion culture;

[0015] After the expansion culture in the secondary expansion tank, the first fermentation tank or the second fermentation tank is inoculated to carry out acetic acid fermentation;

[0016] Preferably, the volume fraction of the first part to the total volume of the culture solution obtained in the first-stage expansion tank is 1-1.5%.

[0017] In an optional embodiment, the filling coefficient of the seed expansion tank and the primary expansion tank is 0.7-0.8, the temperature is 28-32°C, the ventilation coefficient is 0.11-0.14vvm, and the transfer acidity is 2.0-3.0g / 100mL;

[0018] The seed expansion tank is 80-120L, and the first-level expansion tank is 0.8-1.2T.

[0019] In an optional embodiment, the secondary expansion tank is 8-12T, the liquid filling coefficient is 0.7-0.8, the temperature is 31-35°C, the ventilation coefficient is 0.11-0.14vvm, and the transfer acidity is 2.0-3.0g / 100mL.

[0020] In an optional embodiment, the first fermentation tank is 8T-12T, the second fermentation tank is 20T or more, the liquid filling coefficient is 0.65-0.8, the temperature is 31-35°C, the inoculation amount is 10%-20%, and a two-stage oxygenation process is adopted. The ventilation coefficient in the first 5 hours is 0.11-0.12vvm, and the ventilation coefficient after 5 hours is 0.13-0.15vvm;

[0021] The first fermentation tank and the second fermentation tank both control the vinegar base alcohol content to be 4.3-4.8% vol.

[0022] In an optional embodiment, the method further includes filtering and sterilizing the fermentation liquid obtained from the first fermentation tank and the second fermentation tank in sequence.

[0023] In an optional embodiment, in the mixture of hawthorn vinegar and concentrated hawthorn juice, the mass ratio of hawthorn vinegar to concentrated hawthorn juice is (7-9): (1-3);

[0024] The alcohol content of the substrate is 4.0% vol-5.0% vol, and the pH value is 2.4-3.2.

[0025] In an optional embodiment, the wine yeast activation liquid inoculated during the fermentation of hawthorn wine is obtained by culturing and activating wine yeast, and the wine yeast is selected from at least one of Angel RV171, RV002, BV818 and VIC; preferably, the wine yeast is VIC.

[0026] In an optional embodiment, the wine-based sugar source used in the fermentation process of hawthorn wine is selected from at least one of white sugar, whole sucrose syrup, fructose syrup and molasses;

[0027] Preferably, the wine-based sugar source is selected from at least one of sucrose syrup and fructose syrup.

[0028] In an optional embodiment, concentrated hawthorn juice, water and wine-based sugar source are mixed, the soluble solids are controlled to be 18.0-18.5° Brix, the pH value is controlled to be 2.7-3.1, the mixture is cooled to 20-25°C after sterilization, and wine yeast activation liquid is inoculated for anaerobic fermentation, the fermentation temperature is controlled to be 20-25°C, and the mixture is fermented until the soluble solids are ≤8.5° Brix and the alcohol content is ≥7.5% vol;

[0029] Preferably, the concentrated hawthorn juice accounts for 60%-100% of the soluble solid content, and the wine-based sugar source accounts for 0%-40% of the soluble solid content;

[0030] Preferably, after the anaerobic fermentation is completed, filtration and sterilization are performed.

[0031] The present invention has the following beneficial effects: inoculating wine yeast activation liquid for fermentation in the hawthorn wine fermentation stage, being able to tolerate a high acidity environment, and fermenting hawthorn wine with a wine content that meets the requirements; adding a mixture of hawthorn vinegar and concentrated hawthorn juice in the hawthorn vinegar fermentation stage, the addition amount is calculated as the substrate acidity is increased by 0.3-0.5g / 100mL, providing a mixed carbon source for acetic acid bacteria, improving strain activity, shortening the adaptation period, and the new strain 83448-6b-1 independently selected has better acid production performance than traditional CGMCC No.8189, and the alcohol conversion ability of 83448-6b-1 under the same substrate is stronger, and the fermented hawthorn vinegar has a higher acidity, and can also be expanded and applied to the fermentation of hawthorn vinegar of more than 20t, greatly improving production efficiency. The fermentation method provided by the present invention can prepare hawthorn vinegar without the additional addition of an acidity regulator, retaining the functional components of hawthorn to a greater extent, and can also improve the acidity of hawthorn vinegar. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0033] Figure 1 This is the process flow chart of hawthorn wine fermentation;

[0034] Figure 2 This is a process flow chart of hawthorn vinegar fermentation;

[0035] Figure 3 It is the acidity growth curve of different substrate expansion and fermentation process;

[0036] Figure 4 The growth curve of acetic acid bacteria during the expansion and fermentation process of different substrates;

[0037] Figure 5 The curves of soluble solid content change during the expansion and fermentation of different substrates;

[0038] Figure 6 The colony and cell morphology of the self-screened acetic acid bacteria 83448-6b-1 are shown in Figure 1. (a) shows the state in the culture dish; (b) shows the observation under a microscope;

[0039] Figure 7 This is the acidity and acetic acid bacteria growth curve of the control group fermentation test (100L seed tank);

[0040] Figure 8 This is the acidity and acetic acid bacteria growth curve of the 83448-6b-1 fermentation test (100L seed tank);

[0041] Fig. 9 This is a comparison chart of the acidity growth curve of a 100L acetic acid bacteria expansion tank;

[0042] Fig.10 This is a comparison chart of the acidity growth curve of a 1T acetic acid bacteria expansion tank;

[0043] Fig.11 This is a comparison chart of the acidity growth curve of a 10T fermentation tank;

[0044] Fig.12 These are the results of the stability test for strain No. 83448-6b-1. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0046] The embodiment of the present invention provides a hawthorn vinegar fermentation method, including: hawthorn wine fermentation and hawthorn vinegar fermentation. The two fermentation stages are described below respectively:

[0047] S1. Fermentation of Hawthorn Wine

[0048] Please refer to Figure 1 The process of hawthorn wine fermentation includes: mixing concentrated hawthorn juice, water and wine base sugar source to prepare the wine base, inoculating wine yeast activation liquid for fermentation, and obtaining hawthorn original wine. Wine yeast activation liquid is obtained by culturing and activating wine yeast. Wine yeast is selected as a yeast that can better adapt to the high acidity environment of hawthorn and shorten the fermentation time. Because the acidity of hawthorn original juice is high, adding sugar to the wine base can increase the carbon source content of the fermentation substrate and reduce the acidity, which is more conducive to the growth and reproduction of yeast and increases the output of hawthorn original wine.

[0049] In some embodiments, the wine yeast is selected from at least one of Angel RV171, RV002, BV818 and VIC, and the wine yeast can be any one or more of the above; preferably, the wine yeast is VIC. By optimizing the specific type of wine yeast, the fermentation time can be further shortened and the alcohol content of the hawthorn wine can be increased.

[0050] It should be added that the optimum pH of common wine yeast on the market is 3.0-3.6, and brewing yeast is most suitable for growth and reproduction in a slightly acidic pH = 4 environment. In actual fruit wine production, the pH is often between 3.3-3.5. For hawthorn juice or concentrated juice with a pH of ≤ 2.9, it is difficult to find brewing yeast specifically suitable for hawthorn wine fermentation. The inventors compared the fermentation performance of different active dry yeast products on the market and screened out strains suitable for hawthorn wine fermentation to ferment pure hawthorn wine, providing a good foundation for hawthorn vinegar fermentation.

[0051] In some embodiments, the wine-based sugar source used in the fermentation process of hawthorn wine is selected from at least one of white sugar, whole sucrose syrup, fructose syrup and molasses; preferably, the wine-based sugar source is selected from at least one of sucrose syrup and fructose syrup. The use of liquid sugar can reduce the cumbersome white sugar dissolving process, and the raw material cost is lower than that of white sugar, saving labor, material and energy costs.

[0052] Furthermore, the process of fermenting hawthorn wine includes: mixing concentrated hawthorn juice, water and wine-based sugar source, controlling the soluble solids to 18.0-18.5°Brix, controlling the pH value to 2.7-3.1, cooling to 20-25°C after sterilization, inoculating wine yeast activation liquid for anaerobic fermentation, controlling the fermentation temperature to 20-25°C, fermenting until the soluble solids are ≤8.5°Brix, and the alcohol content is ≥7.5%vol. By adjusting the amount of concentrated hawthorn juice, water and wine-based sugar source, the parameters such as soluble solids and pH value meet the requirements.

[0053] Specifically, by adjusting the amount of concentrated hawthorn juice, water and wine-based sugar source, the soluble solids can be 18.0°Brix, 18.1°Brix, 18.2°Brix, 18.3°Brix, 18.4°Brix, 18.5°Brix, etc., and the pH value can be 2.7, 2.8, 2.9, 3.0, 3.1, etc. The fermentation temperature can be 20°C, 21°C, 22°C, 23°C, 24°C, 25°C, etc. When the soluble solids are ≤8.5°Brix and the alcohol content is ≥7.5%vol, the fermentation can be stopped. After the anaerobic fermentation is completed, the hawthorn wine can be filtered and sterilized, and temporarily stored in a clear wine tank.

[0054] Furthermore, the concentrated hawthorn juice, water and the wine-based sugar source are mixed, and the soluble solids are controlled to be 18.0-18.5°Brix, wherein the concentrated hawthorn juice accounts for 60%-100% of the soluble solids content, and the wine-based sugar source accounts for 0%-40% of the soluble solids content. Both the concentrated hawthorn juice and the wine-based sugar source are soluble in water, and it is appropriate to control the ratio of the two within the above range, which can increase the alcohol content of the hawthorn wine.

[0055] According to the embodiment of the present invention, active dry yeast with strong tolerance is selected according to the high acid and low sugar characteristics of hawthorn, and suitable sugar substances are added to ferment hawthorn wine with an alcohol content of 7.5-9.5% vol.

[0056] S2. Fermentation of Hawthorn Vinegar

[0057] The fermentation process of hawthorn vinegar includes: mixing a mixture of hawthorn wine, water, hawthorn vinegar and concentrated hawthorn juice to prepare a vinegar base to obtain a substrate, and then culturing acetic acid bacteria and performing acetic acid fermentation; acetic acid fermentation is to mix the fermentation liquid of the acetic acid bacteria after culturing with the substrate for fermentation to obtain a hawthorn vinegar product with acidity that meets the requirements.

[0058] Wherein, when preparing the substrate, by adjusting the addition amount of the mixture of hawthorn vinegar and concentrated hawthorn juice, the total acid is calculated as acetic acid, so that the acidity of the substrate is increased by 0.3g / 100mL-0.5g / 100mL (such as 0.30g / 100mL, 0.35g / 100mL, 0.40g / 100mL, 0.45g / 100mL, 0.50g / 100mL, etc.), that is:

[0059] The minimum amount to be added is:

[0060]

[0061] The maximum amount of addition is:

[0062]

[0063] Specifically, the mixture of hawthorn vinegar and concentrated hawthorn juice can be detected by a conventional acidity detection method, and the total amount of substrate is calculated based on the capacity of the culture tank and the liquid filling coefficient.

[0064] It should be noted that the acetic acid bacteria is expanded from the laboratory seed preparation to the workshop online seed expansion fermentation. Due to the change of the growth environment, the adaptation period of acetic acid bacteria in the online expansion tank is long, and even the probability of expansion failure is high. Solving whether the laboratory seeds can be successfully transferred to the workshop and the seed expansion is successful plays a key role in realizing industrial fermentation production. In industry, the fermentation medium often uses a mixed carbon source to control the growth of the bacteria and product synthesis quickly or slowly. The use of a mixed carbon source in the fermentation process can often play a role in improving the yield. However, adding an external carbon source increases the cost on the one hand, and on the other hand, it dilutes the flavor concentration of the original juice, resulting in a poor flavor of the product. By regulating the addition amount of the mixture of hawthorn vinegar and concentrated hawthorn juice, the total acid is calculated in acetic acid, and the acidity of the substrate is increased by 0.3g / 100mL-0.5g / 100mL, which can improve the yield while ensuring the flavor of the product.

[0065] In some embodiments, in the mixture of hawthorn vinegar and concentrated hawthorn juice used in the vinegar base preparation, the mass ratio of hawthorn vinegar to concentrated hawthorn juice is (7-9): (1-3), such as 7:3, 7.5:2.5, 8.0:2.0, 8.5:1.5, 9.0:1.0, etc. The alcohol content of the substrate is 4.0% vol-5.0% vol, such as 4.0% vol, 4.5% vol, 5.0% vol, etc. The pH value of the substrate is 2.4-3.2, such as 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, etc.

[0066] The inventor optimized the fermentation bacteria inoculated for acetic acid fermentation. The fermentation bacteria inoculated was 83448-6b-1, which was screened from thermostable acetic acid bacteria CGMCC No.8189. The screening steps were as follows: thermostable acetic acid bacteria CGMCC No.8189 was inoculated into hawthorn wine for cultivation, and when the acidity increased to 2.0g / 100mL, it was transferred and cultured for multiple times in succession. The obtained fermentation liquid was diluted into different concentrations for coating and separation, and continued to be cultured. The strains with large transparent circles and good colony growth were selected for preservation; the strains screened in the initial screening were rescreened to screen out the strains with the best acetic acid production performance. The newly selected strain 83448-6b-1 has better acid production performance than the traditional CGMCC No.8189. Under the same substrate, 83448-6b-1 has stronger alcohol conversion ability, and the fermented hawthorn vinegar has higher acidity. It can also be expanded and applied to the fermentation of hawthorn vinegar of more than 20t, greatly improving production efficiency.

[0067] like Figure 2 As shown, in some embodiments, the process of hawthorn vinegar fermentation includes: culturing the substrate and acetic acid bacteria strains after the vinegar base is prepared in a seed expansion tank, and then entering the first-level expansion tank for mixed culture with the substrate, and the expansion liquid obtained in the first-level expansion tank is divided into two parts, the first part returns to the seed expansion tank for acetic acid bacteria back-inoculation and subculture, and the second part is divided into the following two cases: when the acetic acid bacteria generation is 0, the second part enters the first fermentation tank for acetic acid fermentation; when the acetic acid bacteria generation is greater than or equal to 1, the second part enters the second-level expansion tank for expansion culture; after the second-level expansion tank is expanded and cultured, the first fermentation tank or the second fermentation tank is inoculated for acetic acid fermentation, that is, the culture liquid of one second-level tank is inoculated into several fermentation tanks. The hawthorn vinegar acetic acid expansion and fermentation process provided by the embodiment of the present invention can further improve the fermentation efficiency and is suitable for large-scale production.

[0068] The volume fraction of the first part in the total volume of the culture solution obtained in the first-stage expansion tank is 1-1.5%. By adjusting the proportion of each part, the fermentation efficiency can be further improved.

[0069] Furthermore, the volume of the seed expansion tank is 80-120L, the filling coefficient of the seed expansion tank is 0.7-0.8, the temperature is 28-32°C, the ventilation coefficient is 0.11-0.14vvm, and the transfer acidity is 2.0-3.0g / 100mL. The liquid filling volume is calculated according to the volume and liquid filling coefficient of the seed expansion tank. The liquid filling volume is the sum of the substrate volume and the inoculated acetic acid bacteria volume. The inoculated acetic acid bacteria can be a laboratory 0-generation strain or a strain that is back-transplanted from a primary tank. The ventilation coefficient is conventionally understood, that is, the ventilation ratio, and the unit is vvm, that is, the ratio of the ventilation volume per minute to the liquid volume of the tank. Specifically, the volume of the seed expansion tank can be 80L, 90L, 100L, 110L, 120L, etc.; the filling coefficient of the seed expansion tank can be 0.70, 0.73, 0.75, 0.78, 0.80, etc.; the cultivation temperature of the seed expansion tank can be 28°C, 29°C, 30°C, 31°C, 32°C, etc.; the ventilation coefficient can be 0.11vvm, 0.12vvm, 0.13vvm, 0.14vvm, etc.; the transfer acidity refers to the conditions met when entering the next stage, and the transfer acidity can be 2.0g / 100mL, 2.3g / 100mL, 2.5g / 100mL, 2.8g / 100mL, 3.0g / 100mL, etc.

[0070] Furthermore, the first-stage expansion tank is 0.8-1.2T (tons), the liquid filling coefficient of the first-stage expansion tank is 0.7-0.8, the temperature is 28-32°C, the ventilation coefficient is 0.11-0.14vvm, and the transfer acidity is 2.0-3.0g / 100mL. Specifically, the capacity of the first-level expansion tank can be 0.8T, 0.9T, 1.0T, 1.1T, 1.2T, etc.; the filling coefficient of the first-level expansion tank can be 0.70, 0.73, 0.75, 0.78, 0.80, etc.; the cultivation temperature of the first-level expansion tank can be 28°C, 29°C, 30°C, 31°C, 32°C, etc.; the ventilation coefficient can be 0.11vvm, 0.12vvm, 0.13vvm, 0.14vvm, etc.; the transfer acidity can be 2.0g / 100mL, 2.3g / 100mL, 2.5g / 100mL, 2.8g / 100mL, 3.0g / 100mL, etc.

[0071] Furthermore, the secondary expansion tank is 8-12T, the liquid filling coefficient is 0.7-0.8, the temperature is 31-35°C, the ventilation coefficient is 0.11-0.14, and the transfer acidity is 2.0-3.0g / 100mL. Specifically, the capacity of the secondary expansion tank can be 8T, 9T, 10T, 11T, 12T, etc.; the filling coefficient of the secondary expansion tank can be 0.70, 0.73, 0.75, 0.78, 0.80, etc.; the cultivation temperature of the secondary expansion tank can be 31°C, 32°C, 33°C, 34°C, 35°C, etc.; the ventilation coefficient can be 0.11vvm, 0.12vvm, 0.13vvm, 0.14vvm, etc.; the transfer acidity can be 2.0g / 100mL, 2.3g / 100mL, 2.5g / 100mL, 2.8g / 100mL, 3.0g / 100mL, etc.

[0072] Further, the first fermentation tank is 8T-12T, the second fermentation tank is more than 20T, the liquid filling coefficient is 0.65-0.8, the temperature is 31-35°C, the inoculation amount is 10%-20%, and a two-stage oxygenation process is adopted. The ventilation coefficient in the first 5 hours is 0.11-0.12vvm, and the ventilation coefficient after 5 hours is 0.13-0.15vvm to meet the oxygen demand in different stages; the first fermentation tank and the second fermentation tank both control the vinegar base alcohol content to 4.3-4.8%vol. Specifically, the control conditions of the first fermentation tank and the second fermentation tank are similar, and the specific parameters can be the same or different. The filling coefficient can be 0.65, 0.70, 0.75, 0.78, 0.80, etc.; the fermentation temperature can be 31°C, 32°C, 33°C, 34°C, 35°C, etc.; the inoculation amount refers to the mass proportion of the inoculated fermentation liquid to the liquid volume of the fermentation tank, and the inoculation amount can be 10%, 13%, 15%, 18%, 20%, etc.

[0073] It should be noted that in the fermentation method provided by the embodiment of the present invention, the fermentation substrate and the expansion culture substrate are consistent, and the fermentation temperature of the secondary acetic acid bacteria is consistent with that of the fermentation tank, which greatly shortens the lag period of the growth process of the strain, avoids the extension of the adaptation period caused by the switching of nutrients or temperature, that is, the growth environment of acetic acid bacteria, affecting the production efficiency and even having a negative effect on the activity of acetic acid bacteria.

[0074] In some embodiments, the fermentation liquid obtained from the first fermentation tank and the second fermentation tank is filtered and sterilized in sequence, and then the original vinegar is stored. The filtering method is not limited, such as disc filtration; the sterilization method is not limited, such as UHT sterilization.

[0075] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0076] Example 1

[0077] This embodiment provides a hawthorn vinegar fermentation method, including two stages of hawthorn wine fermentation and hawthorn vinegar fermentation, as follows:

[0078] (1) Hawthorn wine fermentation

[0079] Provide wine yeast activation solution: put commercially purchased wine yeast (model VIC) into 10 times more 35℃ sterile water for activation for 20 minutes.

[0080] Concentrated hawthorn juice is provided: commercially available raw materials, soluble solids 59.6°Brix, acidity 7.33g / 100mL.

[0081] Provide softened water: hardness ≤80.0mg / L, pH7.50-8.50, total colony count ≤100CFUmL, mold and yeast ≤5CFUmL.

[0082] After 2.6T of concentrated hawthorn juice was partially reconstituted with 10.4T of softened water, 1T of white sugar was added to adjust the soluble solids of the wine base to 18.3°Brix, pH=2.9, sterilized at 75°C for 20min, inoculated with wine yeast activation liquid (inoculation amount of 0.04%) after cooling to 25°C, and the anaerobic fermentation temperature was 25°C. When the soluble solids were ≤8.5°Brix and the alcohol content was ≥7.5%vol, the fermentation was stopped, the hawthorn wine was filtered, the hawthorn wine was sterilized, and temporarily stored in a clear wine tank.

[0083] (2) Fermentation of Hawthorn Vinegar

[0084] Providing hawthorn vinegar: acidity 4.98g / 100mL.

[0085] A mixture of hawthorn vinegar and concentrated hawthorn juice is provided: the mixture of hawthorn vinegar and concentrated hawthorn juice is obtained by mixing the hawthorn vinegar and concentrated hawthorn juice in a mass ratio of 9:1, and the acidity is 5.20 g / 100 mL. The parameters of the concentrated hawthorn juice are as shown in step (1).

[0086] Providing a vinegar-based substrate: 28.5 T of hawthorn wine (prepared in step (1)), 17.6 T of softened water, and 3.9 T of a mixture of hawthorn vinegar and concentrated hawthorn juice are mixed to obtain a substrate, wherein the mixture of hawthorn vinegar and concentrated hawthorn juice is added to increase the acidity of the substrate (total acid in terms of acetic acid) by 0.4 g / 100 mL, and the prepared substrate has an alcohol content of 4.5% vol and a pH value of 2.72.

[0087] The vinegar-based substrate and acetic acid bacteria (accession number CGMCC No. 8189) are cultured in a seed expansion tank, and then mixed with the substrate in a primary expansion tank. After the expansion is completed, the substrate is mixed with the substrate in the first fermentation tank (10T) for acetic acid fermentation. The fermentation liquid obtained in the first fermentation tank is subjected to disc filtration, UHT sterilization, and original vinegar storage.

[0088] Seed expansion tank parameters: the seed expansion tank is 100L, the liquid filling coefficient is 0.75, the acetic acid bacteria strain inoculation amount is 10% (i.e. the ratio of the mass of the acetic acid bacteria strain to the total amount of liquid filling), the temperature is 30°C, the ventilation coefficient is 0.12vvm, and the transfer acidity is 2.5g / 100mL.

[0089] Parameters of the first-stage expansion tank: the first-stage expansion tank is 1T, the liquid filling coefficient is 0.75, the temperature is 30℃, the ventilation coefficient is 0.12vvm, and the transfer acidity is 2.5g / 100mL.

[0090] Parameters of the first fermentation tank: The first fermentation tank is 10T, the liquid filling coefficient is 0.75, the temperature is 33°C, the inoculation amount is 10%, two-stage oxygenation is adopted, the ventilation coefficient is 0.11vvm in the first 5h, and the ventilation coefficient is 0.14vvm after 5h; the vinegar base alcohol content is 4.5%vol.

[0091] Examples 2-4 and Comparative Examples 1-2 are compared with respect to the yeast used in step (1):

[0092] Example 2

[0093] This embodiment provides a hawthorn vinegar fermentation method, which is different from the embodiment 1 only in that the yeast used in preparing the wine yeast activation solution in step (1) is commercially available wine yeast (model: Angel RV171).

[0094] Example 3

[0095] This embodiment provides a hawthorn vinegar fermentation method, which is different from the embodiment 1 only in that the yeast used in preparing the wine yeast activation solution in step (1) is commercially available wine yeast (model: Angel RV002).

[0096] Example 4

[0097] This embodiment provides a hawthorn vinegar fermentation method, which is different from the embodiment 1 only in that the yeast used in preparing the wine yeast activation solution in step (1) is commercially available wine yeast (model: Angel BV818).

[0098] Comparative Example 1

[0099] This comparative example provides a hawthorn vinegar fermentation method, which is different from Example 1 only in that the yeast used in preparing the wine yeast activation solution in step (1) is commercially available white wine yeast (model: Fali winemaking high-activity dry yeast).

[0100] Comparative Example 2

[0101] This comparative example provides a hawthorn vinegar fermentation method, which is different from Example 1 only in that the yeast used in preparing the wine yeast activation solution in step (1) is commercially available white wine yeast (model: Angel winemaking high-activity dry yeast).

[0102] The fermentation time of the hawthorn wine preparation process of Examples 1-4 and Comparative Examples 1-2 was tested to obtain the residual sugar and alcohol content of the hawthorn wine. The results are shown in Table 1.

[0103] Table 1 Comparison of fermentation effects of Examples 1-4 and Comparative Examples 1-2

[0104]

[0105]

[0106] As can be seen from Table 1, the wine yeast used in Example 1 has a short fermentation time and a high wine yield.

[0107] Example 1 and Examples 5-8 are compared with respect to the wine-based sugar source used in step (1):

[0108] Example 5

[0109] This embodiment provides a hawthorn vinegar fermentation method, which is different from the embodiment 1 only in that the white sugar in step (1) is replaced by an equal amount of sucrose syrup, and the sucrose syrup is converted according to the soluble solid content.

[0110] Example 6

[0111] This embodiment provides a hawthorn vinegar fermentation method, which is different from the embodiment 1 only in that the white sugar in step (1) is replaced by an equal amount of fructose-glucose syrup, and the fructose-glucose syrup is converted according to the soluble solid content.

[0112] Example 7

[0113] This embodiment provides a hawthorn vinegar fermentation method, which is different from the embodiment 1 only in that the white sugar in step (1) is replaced by an equal amount of molasses, and the molasses is converted according to the soluble solid content.

[0114] Example 8

[0115] This embodiment provides a method for fermenting hawthorn vinegar, which differs from the embodiment 1 only in that the white sugar in step (1) is replaced by an equal amount of molasses and fructose syrup, and the molasses and fructose syrup mixture is converted according to the soluble solid content. The preparation process of the molasses and fructose syrup mixture is as follows: molasses and fructose syrup are mixed in a mass ratio of 1:9.

[0116] The fermentation time of the hawthorn wine preparation process of Example 1 and Examples 5-8 was tested to obtain the residual sugar and alcohol content of the hawthorn wine. The results are shown in Table 2.

[0117] Table 2 Comparison of fermentation effects of Example 1 and Examples 5-8

[0118]

[0119] If white sugar is used as the wine-based raw material, a sugar dissolving process is required in industrial production. This process is cumbersome and time-consuming, and is not practical for efficient large-scale industrial production. If liquid sugar is used as the raw material, labor costs can be reduced while improving production efficiency. It can be seen from the test data in Table 2 that the preferred wine-based sugar sources are hawthorn juice plus sucrose syrup and hawthorn juice plus fructose syrup.

[0120] Example 1 and Comparative Example 3 are compared with respect to the composition of the substrate:

[0121] Comparative Example 3

[0122] This comparative example provides a hawthorn vinegar fermentation method, which differs from Example 1 only in that the mixture of hawthorn vinegar and concentrated hawthorn juice is not added to the substrate in step (2).

[0123] The fermentation process of the 100L seed expansion tank in the test example 1 and the comparative example 3 is shown in Figure 3 , Figure 4 and Figure 5 . Figure 3 The acidity growth curve of different substrate expansion and fermentation process. Figure 4 The growth curve of acetic acid bacteria in different substrate expansion and fermentation processes. Figure 5 This is the change curve of soluble solids during the expansion and fermentation process of different substrates.

[0124] It can be seen that after adding a certain amount of the mixed carbon source of hawthorn vinegar and concentrated hawthorn juice, within 60 hours of expansion and propagation, although the acidity increased slowly, the OD600 reflecting the propagation of acetic acid bacteria gradually increased, and the final acidity could reach about 4.5.

[0125] About the selection of acetic acid bacteria strains:

[0126] Example 9

[0127] This comparative example provides a method for fermenting hawthorn vinegar, which is mainly different from Example 1 in that the fermentation bacteria inoculated in the seed expansion tank in step (2) are No. 83448-6b-1, and the preparation process of the fermentation bacteria No. 83448-6b-1 is described below. The method for fermenting hawthorn vinegar is as follows:

[0128] (1) Hawthorn wine fermentation

[0129] Refer to Example 1.

[0130] (2) Fermentation of Hawthorn Vinegar

[0131] Providing hawthorn vinegar: acidity 4.98g / 100mL.

[0132] A mixture of hawthorn vinegar and concentrated hawthorn juice is provided: the mixture of hawthorn vinegar and concentrated hawthorn juice is obtained by mixing the hawthorn vinegar and concentrated hawthorn juice in a mass ratio of 9:1, and the acidity is 5.20 g / 100 mL. The parameters of the concentrated hawthorn juice are as shown in step (1).

[0133] Providing a vinegar-based substrate: 28.5 T of hawthorn wine (prepared in step (1)), 17.6 T of softened water, and 3.9 T of a mixture of hawthorn vinegar and concentrated hawthorn juice are mixed to obtain a substrate, wherein the mixture of hawthorn vinegar and concentrated hawthorn juice is added to increase the acidity of the substrate (total acid in terms of acetic acid) by 0.4 g / 100 mL, and the prepared substrate has an alcohol content of 4.5% vol and a pH value of 2.72.

[0134] The substrate and acetic acid bacteria strain (the fermentation bacteria inoculated is 83448-6b-1) after the vinegar base is prepared are cultured in a seed expansion tank, and then enter the first-level expansion tank for mixed culture with the substrate. The culture solution obtained in the first-level expansion tank is divided into two parts. The first part returns to the seed expansion tank for back-inoculation and subculture, and the strain generation increases by 1 generation accordingly, that is, the 1st generation strain; the second part of the 0th generation strain in the first-level expansion tank is inoculated into the first fermentation tank (10T) for acetic acid fermentation. When the strain generation is ≥1 generation, the second part of the first-level expansion tank enters the second-level expansion tank to continue the acetic acid bacteria expansion. After the expansion, it enters the first fermentation tank (10T) or the second fermentation tank (20T or more) and mixes with the substrate for acetic acid fermentation. The fermentation solution obtained from the first fermentation tank and the second fermentation tank is subjected to disc filtration, UHT sterilization, and original vinegar storage. The volume fraction of the first part in the total amount of the culture solution obtained in the first expansion tank is 1%.

[0135] Seed expansion tank parameters: the seed expansion tank is 100L, the liquid filling coefficient is 0.75, the acetic acid bacteria strain inoculation amount is 10% (i.e. the ratio of the mass of the acetic acid bacteria strain to the total amount of liquid filling), the temperature is 30°C, the ventilation coefficient is 0.12vvm, and the transfer acidity is 2.5g / 100mL.

[0136] Parameters of the first-stage expansion tank: the first-stage expansion tank is 1T, the liquid filling coefficient is 0.75, the temperature is 30℃, the ventilation coefficient is 0.12vvm, and the transfer acidity is 2.5g / 100mL.

[0137] Secondary expansion tank parameters: The secondary expansion tank is 10T, the liquid filling coefficient is 0.75, the temperature is 33℃, the ventilation coefficient is 0.12vvm, and the transfer acidity is 2.5g / 100mL.

[0138] Parameters of the first fermentation tank: The first fermentation tank is 10T, the liquid filling coefficient is 0.75, the temperature is 33°C, the inoculation amount is 10%, two-stage oxygenation is adopted, the ventilation coefficient is 0.11vvm in the first 5h, and the ventilation coefficient is 0.14vvm after 5h; the vinegar base alcohol content is 4.5%vol.

[0139] Parameters of the second fermentation tank: The second fermentation tank is ≥20T, the liquid filling coefficient is 0.7, the temperature is 33°C, the inoculation amount is 17.5%, two-stage oxygenation is adopted, the ventilation coefficient is 0.11vvm in the first 5 hours, and the ventilation coefficient is 0.14vvm after 5 hours; the vinegar base alcohol content is 4.5%vol.

[0140] Under the high acid stress of hawthorn wine, the metabolism of acetic acid bacteria cells and acetic acid fermentation are slow. The fermentation time of hawthorn vinegar is significantly longer than that of ordinary fruit vinegar, and the alcohol conversion rate is low. Therefore, it is necessary to select acetic acid bacteria with excellent tolerance and acid production performance for hawthorn vinegar fermentation, which can effectively shorten the fermentation time and improve the alcohol conversion rate.

[0141] Example 9 Isolation and Screening of Strain 83448-6b-1

[0142] (1) Strain selection

[0143] The company's own patent CN201310549668.7 thermostable acetic acid bacteria CGMCC No.8189 was inoculated into 4.5-5.5%vol hawthorn wine, and continuous subculture was carried out in a shaking table at 30℃ and 220r / min. When the acidity increased to 2.0g / 100mL, the culture was transferred and continuous subculture was carried out for more than seven times.

[0144] (2) Strain isolation and initial screening

[0145] Dilute the seventh and above fermentation broth with sterile water to 10 -5 , 10 -6 , 10 -7 , 10 -8 Take 100 μl of each gradient solution and spread it evenly on the surface of the primary screening solid culture medium. Culture it at 30°C for 48 h. Select the strains with large transparent zones and good colony growth and store them in the slant culture medium.

[0146] Initial screening of solid culture medium ingredients: glucose 25g / L, yeast extract powder 20g / L, anhydrous ethanol 4% (v / v), CaCO3 20g / L, technical agar powder 20g / L;

[0147] Slant culture medium composition: glucose 25g / L, yeast extract powder 20g / L, anhydrous ethanol 3% (v / v), CaCO3 20g / L, technical agar powder 20g / L;

[0148] (3) Rescreening and acid production assessment

[0149] The strains screened initially were streaked on the surface of the rescreened solid culture medium, cultured at 30°C for 48 hours, and strains with large transparent circles and good colony growth were selected and stored in slant culture medium. The screened strains were inoculated into the basic liquid culture medium, cultured in a shaking incubator at 30°C and 220r / min, transferred to the fermentation liquid culture medium at an acidity of 2.0g / 100mL, and cultured in a shaking incubator at 30°C and 220r / min. The acid production performance of the strains was evaluated, and the total acid (in terms of acetic acid) content was titrated with sodium hydroxide. The strain with the best acid production performance was obtained (No. 83448-6b-1).

[0150] Rescreened solid culture medium ingredients: glucose 25g / L, yeast extract powder 20g / L, anhydrous ethanol 5% (v / v), CaCO3 20g / L, technical agar powder 20g / L;

[0151] Basic liquid culture medium ingredients: glucose 25 g / L, yeast extract powder 20 g / L, anhydrous ethanol 4% (v / v);

[0152] Fermentation liquid medium composition: Mix demineralized water and hawthorn wine, and adjust the alcohol content to 4.3% vol. (4) Strain preservation and stability evaluation

[0153] The slant No. 83448-6b-1 was stored in a refrigerator at low temperature and transferred to a blank slant medium for subculture every 15 days, with 3 slants transferred each time. In the next transfer, the slant with the most calcium carbonate consumption was used as the subculture strain. When the continuous subculture lasted for more than half a year, it was inoculated into the basic liquid culture medium and cultured in a shaking incubator at 30°C and 220r / min. When the acidity was 2.0g / 100mL, it was transferred to the fermentation liquid culture medium and cultured in a shaking incubator at 30°C and 220r / min. The fermentation stability of the strain was evaluated and the total acid (in terms of acetic acid) content was titrated with sodium hydroxide.

[0154] like Fig.12 As shown, the acid production performance of strain No. 83448-6b-1 after continuous slant propagation for half a year was not much different from that in the acid production evaluation of step (3), indicating that the stability of slant propagation was good.

[0155] Compared with the original strain, strain No. 83448-6b-1 is more adaptable to the hawthorn wine environment, the expansion and fermentation time is significantly shortened, and the alcohol conversion rate is higher.

[0156] Figure 6 These are the colonies and cell morphology of the self-screened acetic acid bacteria 83448-6b-1. (a) shows the state in the culture dish; (b) shows the observation under a microscope.

[0157] Comparison of the online 100L seed tank of self-screened acetic acid bacteria 83448-6b-1 and CCMCCNO.8189 (control group) using a mixture of hawthorn vinegar and concentrated hawthorn juice:

[0158] Softened water and hawthorn wine were used for preparation, and the acidity of the substrate was increased by 0.4 g / 100 mL. Hawthorn vinegar (total acid as acetic acid ≥ 4.2 g / 100 mL) was added: concentrated hawthorn juice mixture = 9:1 (by mass). At this time, the vinegar base wine content was 4.5% vol, the soluble solids were 5.3° Brix, and the pH was 2.88.

[0159] Figure 7 This is the acidity and acetic acid bacteria growth curve of the control group fermentation test (100L seed tank); Figure 8 The acidity and acetic acid bacteria growth curve of the 83448-6b-1 fermentation test (100L seed tank). It was found that the acetic acid bacteria selected by mutation can quickly adapt to the culture environment of pH ≤ 3.0, shorten the fermentation cycle by 29.4%, and the conversion rate is 17.3% higher than that of the control group.

[0160] Note: Figure 7 , Fig. 9 , Fig.10 and Fig.11 The control group in Example 1.

[0161] The comparison of the 0th generation expansion and fermentation of the strain (100L expansion tank to 10T tank fermentation) is shown in Table 3:

[0162] Table 3 Comparison of the expansion and fermentation of two strains at generation 0

[0163]

[0164] Fig. 9 This is a comparison chart of the acidity growth curve of a 100L acetic acid bacteria expansion tank. Fig.10 This is a comparison chart of the acidity growth curve of the 1T acetic acid bacteria expansion tank. Fig.11 The figure is a comparison of the acidity growth curve of the 10T fermentation tank. It can be seen that the performance of the acetic acid bacteria selected by mutation is better than that of the control group in the step-by-step expansion culture and fermentation.

[0165] Test strains of different generations of expansion and fermentation:

[0166] The substrate was prepared with a mixture of softened water, hawthorn wine, hawthorn vinegar and concentrated hawthorn juice (see Example 1 for specific parameters), and the batch fermentation method was adopted to inoculate different generations of bacteria into the online 100L expansion tank to 20T and above tanks for fermentation. The results are shown in Tables 4 and 5:

[0167] Table 4 Comparison of the effects of different generations of bacterial strains

[0168]

[0169]

[0170] Table 5 Comparison of fermentation effects of different generations of bacteria

[0171]

[0172] *(When acetic acid bacteria are inoculated into the seed tank for expansion, it is recorded as the 0th generation of bacteria. The number of generations of bacteria is calculated by adding one generation when the first-level tank is inoculated back into the seed tank);

[0173] It has been found that too young a seed age leads to slow growth of the strain in the early stage, prolonged fermentation cycle, high energy consumption in production, and low equipment utilization. Therefore, the seed age is too low and is not suitable for direct large-scale fermentation. The strain can still maintain good fermentation performance after more than six generations. Because the acid production performance of the 0th generation strain is poorer than that of the first generation and above, the 0th generation strain is arranged for single batch fermentation in a 10t tank to reduce the waste of production energy consumption. When the acetic acid bacteria are passed to more than one generation, the 10t tank is arranged as an expansion tank and transferred to a ≥20t fermentation tank for acetic acid fermentation.

[0174] Example 1 and Examples 10-11 and Comparative Examples 4-5 are compared with respect to the amount of the mixture of hawthorn vinegar and concentrated hawthorn juice in the substrate:

[0175] Example 10

[0176] The present embodiment provides a hawthorn vinegar fermentation method, which differs from the embodiment 9 only in that: the amount of the mixture of hawthorn vinegar and concentrated hawthorn juice in the composition of the substrate is increased by 0.3 g / 100 mL of the added mixture of hawthorn vinegar and concentrated hawthorn juice to increase the acidity of the substrate (total acid as acetic acid).

[0177] Embodiment 11

[0178] The present embodiment provides a hawthorn vinegar fermentation method, which differs from the embodiment 9 only in that: the amount of the mixture of hawthorn vinegar and concentrated hawthorn juice in the composition of the substrate is increased by 0.5 g / 100 mL of the added mixture of hawthorn vinegar and concentrated hawthorn juice.

[0179] Comparative Example 4

[0180] This comparative example provides a hawthorn vinegar fermentation method, which differs from Example 9 only in that: the amount of the mixture of hawthorn vinegar and concentrated hawthorn juice in the composition of the substrate is increased by 0.2 g / 100 mL of the added mixture of hawthorn vinegar and concentrated hawthorn juice.

[0181] Comparative Example 5

[0182] This comparative example provides a hawthorn vinegar fermentation method, which differs from Example 9 only in that: the amount of the mixture of hawthorn vinegar and concentrated hawthorn juice in the composition of the substrate is increased by 0.6 g / 100 mL of the added mixture of hawthorn vinegar and concentrated hawthorn juice to increase the acidity of the substrate (total acid as acetic acid).

[0183] The fermentation performance results of Test Example 1, Examples 10-11 and Comparative Examples 4-5 are shown in Table 6.

[0184] Table 6 Fermentation performance results of Example 1, Examples 10-11 and Comparative Examples 4-5 It can be seen that the alcohol conversion rates of Examples 9-10 and Comparative Examples 4-5 are significantly higher than that of Example 1, but the fermentation time of Comparative Examples 4-5 is significantly longer than that of Examples 9-10.

[0185] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for fermenting hawthorn vinegar, characterized in that: include: Fermentation of hawthorn wine and hawthorn vinegar; The process of fermenting hawthorn wine comprises: mixing concentrated hawthorn juice, water and a wine-based sugar source, inoculating wine yeast activation liquid for fermentation, and obtaining hawthorn original wine; The process of fermenting hawthorn vinegar comprises: preparing a mixture of the hawthorn wine, water, hawthorn vinegar and concentrated hawthorn juice into a substrate, carrying out acetic acid bacteria expansion and acetic acid fermentation; the acetic acid fermentation is to mix the fermentation liquid after the acetic acid bacteria expansion with the substrate for fermentation; Wherein, when preparing the substrate, by adjusting the addition amount of the mixture of the hawthorn vinegar and the concentrated hawthorn juice, the total acid is calculated as acetic acid, so that the acidity of the substrate is increased by 0.3g / 100mL-0.5g / 100mL.

2. The hawthorn vinegar fermentation method according to claim 1, characterized in that: In the acetic acid fermentation process, the acetic acid bacteria used is 83448-6b-1, which is screened from the thermostable acetic acid bacteria CGMCC No.8189, and the screening steps are as follows: The thermostable acetic acid bacteria CGMCC No.8189 was inoculated into hawthorn wine for cultivation. When the acidity increased to 2.0g / 100mL, the culture was continued for multiple times. The fermentation liquid was diluted into different concentrations for coating and separation. The strains with large transparent circles and good colony growth were selected for preservation. The strains screened initially were rescreened to select the strains with the best acetic acid production performance. Preferably, the process of fermenting the hawthorn vinegar comprises: culturing the substrate and the acetic acid bacteria in a seed expansion tank, and then entering a primary expansion tank for mixed culture with the substrate, the expansion liquid obtained in the primary expansion tank is divided into two parts, the first part returns to the seed expansion tank for acetic acid bacteria back-inoculation and subculture, and the second part is divided into the following two situations: when the acetic acid bacteria generation number is 0, the second part enters the first fermentation tank for acetic acid fermentation; when the acetic acid bacteria generation number is greater than or equal to 1, the second part enters the secondary expansion tank for expansion culture; After the expansion culture in the secondary expansion tank, the first fermentation tank or the second fermentation tank is inoculated to carry out acetic acid fermentation; Preferably, the volume fraction of the first part to the total volume of the culture solution obtained in the first-stage expansion tank is 1-1.5%.

3. The hawthorn vinegar fermentation method according to claim 2, characterized in that: The filling coefficient of the seed expansion tank and the first-level expansion tank is 0.7-0.8, the temperature is 28-32°C, the ventilation coefficient is 0.11-0.14vvm, and the transfer acidity is 2.0-3.0g / 100mL; The seed expansion tank is 80-120L, and the first-level expansion tank is 0.8-1.2T.

4. The hawthorn vinegar fermentation method according to claim 2, characterized in that: The secondary expansion tank has a capacity of 8-12T, a liquid filling coefficient of 0.7-0.8, a temperature of 31-35°C, a ventilation coefficient of 0.11-0.14vvm, and a transfer acidity of 2.0-3.0g / 100mL.

5. The hawthorn vinegar fermentation method according to claim 2, characterized in that: The first fermentation tank is 8T-12T, the second fermentation tank is more than 20T, the liquid filling coefficient is 0.65-0.8, the temperature is 31-35°C, the inoculation amount is 10%-20%, and a two-stage oxygenation process is adopted. The ventilation coefficient in the first 5 hours is 0.11-0.12vvm, and the ventilation coefficient after 5 hours is 0.13-0.15vvm; The first fermentation tank and the second fermentation tank both control the vinegar-based alcohol content to be 4.3-4.8% vol.

6. The hawthorn vinegar fermentation method according to claim 2, characterized in that: The method also includes filtering and sterilizing the fermentation liquid obtained from the first fermentation tank and the second fermentation tank in sequence.

7. The hawthorn vinegar fermentation method according to any one of claims 1 to 6, characterized in that: In the mixture of hawthorn vinegar and concentrated hawthorn juice, the mass ratio of hawthorn vinegar to concentrated hawthorn juice is (7-9):(1-3); The alcohol content of the substrate is 4.0% vol-5.0% vol, and the pH value is 2.4-3.

2.

8. The hawthorn vinegar fermentation method according to claim 1, characterized in that: The wine yeast activation liquid inoculated during the fermentation of the hawthorn wine is obtained by culturing and activating wine yeast, and the wine yeast is selected from at least one of Angel RV171, RV002, BV818 and VIC; preferably, the wine yeast is VIC.

9. The hawthorn vinegar fermentation method according to claim 8, characterized in that: The wine-based sugar source used in the fermentation process of the hawthorn wine is selected from at least one of white sugar, whole sucrose syrup, fructose syrup and molasses; Preferably, the wine-based sugar source is selected from at least one of sucrose syrup and fructose syrup.

10. The hawthorn vinegar fermentation method according to claim 8 or 9, characterized in that: The concentrated hawthorn juice, water and wine-based sugar source are mixed, the soluble solids are controlled to be 18.0-18.5°Brix, the pH value is controlled to be 2.7-3.1, the mixture is cooled to 20-25°C after sterilization, the wine yeast activation liquid is inoculated for anaerobic fermentation, the fermentation temperature is controlled to be 20-25°C, and the fermentation is carried out until the soluble solids are ≤8.5°Brix and the alcohol content is ≥7.5%vol; Preferably, the concentrated hawthorn juice accounts for 60%-100% of the soluble solid content, and the wine-based sugar source accounts for 0%-40% of the soluble solid content; Preferably, after the anaerobic fermentation is completed, filtration and sterilization are performed.

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