Composite acetic bacteria agent for preparing termitomyces albuminosus vinegar as well as preparation method and application of composite acetic bacteria agent

Abstract

The invention belongs to the technical field of vinegar brewing, and particularly relates to a composite acetic bacteria agent for preparing termitomyces albuminosus vinegar as well as a preparation method and application of the composite acetic bacteria agent. The composite acetic bacteria agent provided by the invention is prepared from acetobacter pasteurianus d739 and acetobacter aceti d1042 according to a specific proportion, and when the composite acetic bacteria agent provided by the invention is added into the fermented termitomyces albuminosus vinegar, the content of total phenols and total flavonoids in the termitomyces albuminosus vinegar can be increased, the capability of removing DPPH free radicals and ABTS free radicals is improved, and the yield of the termitomyces albuminosus vinegar is increased. The iron ion reduction capability is improved; in addition, the enzyme activity related to blood sugar and blood fat reduction can be remarkably improved, the quality of the termitomyces albuminosus vinegar is improved, and the vinegar is endowed with more complex flavor levels and anti-oxidation characteristics.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of vinegar brewing, and more particularly relates to a compound acetic acid bacteria agent for preparing black-bark chicken nest fungus vinegar, a preparation method thereof and application. BACKGROUND

[0002] Black-bark chicken nest fungus (Daedalea dickinsii) is a symbiotic basidiomycete with significant ecological and economic value. Termitomyces eurrhizus Its fruiting body is tender and has a rich and delicious taste, and is rich in flavor nucleotides such as guanylic acid and free amino acids such as glutamic acid. It is a high-quality edible and medicinal fungus. At the same time, its nutritional characteristics of high protein (dry weight accounting for 28%~32%), polysaccharides (such as beta-glucan) and trace elements such as selenium and zinc make it an ideal raw material for functional food development, thus meeting the market demand of modern food industry for natural and healthy ingredients.

[0003] The types and quantities of microorganisms directly affect the composition of various functional ingredients in black-bark chicken nest fungus vinegar, and determine the quality of black-bark chicken nest fungus vinegar. However, due to the openness of the fermentation process, the complexity and diversity of the mixed fermentation system of multiple enzymes and bacteria, and the difficulty in monitoring and controlling the fermentation, many factors often lead to unstable quality of black-bark chicken nest fungus vinegar.

[0004] Adding functional strains during the brewing process of vinegar can significantly improve the efficiency and quality of vinegar brewing, increase the conversion rate of ethanol-acetic acid, and shorten the fermentation period. It can also give vinegar more complex flavor levels and antioxidant properties. The types and quantities of functional microorganisms contained in the fermentation of black-bark chicken nest fungus vinegar are the key to determining the quality of black-bark chicken nest fungus vinegar. Therefore, in order to improve and enhance the quality of black-bark chicken nest fungus vinegar, it is necessary to add compound microorganisms during the production of black-bark chicken nest fungus vinegar, optimize the high-quality functional ingredients contained in the black-bark chicken nest fungus vinegar prepared by the existing traditional process, and stabilize and enhance the quality of black-bark chicken nest fungus vinegar. However, the existing microorganisms for preparing black-bark chicken nest fungus vinegar have low and few improving effects on the functional substances in black-bark chicken nest fungus vinegar. SUMMARY

[0005] In view of the above technical problems, the present application provides a compound acetic acid bacteria agent for preparing black-bark chicken nest fungus vinegar, a preparation method thereof and application.

[0006] The present application specifically adopts the following technical solutions: The present application provides a compound acetic acid bacteria agent, the active ingredients of which include: Acetobacter pasteurii d739 and Acetobacter fruiticola d1042. Acetobacter pasteurianus The classification name of the Acetobacter pasteurii d739 is Acetobacter pomorum, and is preserved in China General Microbiological Culture Collection Center, with a preservation number of CGMCC No. 34005 and a preservation date of March 28, 2025, and the ratio of viable bacterial numbers of the Acetobacter pasteurianus d739 and the Acetobacter pomum d1042 in the compound acetic acid bacteria agent is 0.5~1.5:0.5~1.5.

[0007] The Acetobacter pasteurianus d739 and the Acetobacter pomum d1042 are separated from vinegar grains, and the compound acetic acid bacteria agent is obtained by mixing the two bacteria in a specific ratio.

[0008] The application provides a preparation method of the compound acetic acid bacteria agent, and the method comprises the following steps: inoculating the Acetobacter pasteurianus d739 and the Acetobacter pomum d1042 into culture media respectively for culture, so as to obtain Acetobacter pasteurianus d739 bacterial liquid and Acetobacter pomum d1042 bacterial liquid respectively, and then mixing the Acetobacter pasteurianus d739 bacterial liquid and the Acetobacter pomum d1042 bacterial liquid in equal volume ratio to obtain the compound bacteria agent.

[0009] The application further provides black skin chicken mushroom vinegar prepared from the compound acetic acid bacteria agent. S1, mixing black skin chicken mushroom powder and water in a mass-volume ratio of 0.5~1.5g:15~25mL, adding white granulated sugar to adjust the sugar degree to 15~20°Brix, sterilizing to obtain black skin chicken mushroom stock solution; S2, dissolving 0.5~1.5g of yeast powder in 95~105mL of water to obtain a yeast solution, adding 2%~3% of Daqu by volume fraction and 1%~3% of the yeast solution by volume fraction to the black skin chicken mushroom stock solution, and then mixing and fermenting at 25~30℃ and 150~200r / min for 7~9 days to obtain a fermentation liquor; S3, adjusting the alcohol content of the fermentation liquor to 0.01~0.1g / mL, adding 20%~30% of the compound acetic acid bacteria agent by volume fraction, taking the fermentation end point of 4%~6% of acidity and less than 0.5%~1.5% of alcohol content, and then fermenting at 32~37℃ and 150~200r / min to the end point to obtain black skin chicken mushroom vinegar.

[0010] The application further provides application of the compound acetic acid bacteria agent in preparation of black skin chicken mushroom vinegar.

[0011] Further, the compound acetic acid bacteria agent is used for increasing the content of total phenol, total flavone and total acid in black skin chicken mushroom vinegar. Further, the complex acetic acid bacteria agent is used for improving the antioxidant effect, the sugar-lowering effect and the lipid-lowering effect of the black-bark chicken nest fungus vinegar.

[0012] Further, the improvement of the antioxidant effect of the black-bark chicken nest fungus vinegar comprises improvement of the iron ion reducing power, the DPPH free radical scavenging rate and the ABTS free radical scavenging rate, Further, the improvement of the sugar-lowering effect of the black-bark chicken nest fungus vinegar comprises improvement of the alpha-amylase inhibition rate and the alpha-glucosidase inhibition rate, Further, the improvement of the lipid-lowering effect of the black-bark chicken nest fungus vinegar comprises improvement of the cholesterol removal rate, the pancreatic lipase inhibition rate and the bile salt hydrolase specific enzyme activity.

[0013] The present application has the following beneficial effects: The complex acetic acid bacteria agent provided by the present application can provide the total phenol content and the total flavonoid content in the black-bark chicken nest fungus vinegar, improve the quality of the black-bark chicken nest fungus vinegar, improve the DPPH free radical scavenging ability and the ABTS free radical scavenging ability, improve the antioxidant properties, significantly improve the sugar-lowering and lipid-lowering enzyme activities, and endow the vinegar with more complex flavor levels. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 It is a morphological identification diagram of the Bacillus pasteurii d739.

[0015] Figure 2 It is a morphological identification diagram of the Acetobacter fruit d1042.

[0016] Figure 3 It is a sugar content change statistical diagram in the fermentation process of the black-bark chicken nest fungus vinegar.

[0017] Figure 4 It is a pH change statistical diagram in the fermentation process of the black-bark chicken nest fungus vinegar.

[0018] Figure 5 It is an alcohol content change statistical diagram in the fermentation process of the black-bark chicken nest fungus vinegar.

[0019] Figure 6 It is a total acid change statistical diagram in the fermentation process of the black-bark chicken nest fungus vinegar.

[0020] Figure 7 It is a total phenol content change statistical diagram in the fermentation process of the black-bark chicken nest fungus vinegar.

[0021] Figure 8 It is a total flavonoid content change statistical diagram in the fermentation process of the black-bark chicken nest fungus vinegar.

[0022] Figure 9 It is an iron ion reducing power change statistical diagram in the fermentation process of the black-bark chicken nest fungus vinegar.

[0023] Figure 10The figure for the change of DPPH free radical scavenging rate in the fermentation process of black-skin chicken nest fungus vinegar.

[0024] Figure 11 The figure for the change of ABTS free radical scavenging rate in the fermentation process of black-skin chicken nest fungus vinegar.

[0025] Figure 12 The figure for the change of α-amylase inhibition rate in the fermentation process of black-skin chicken nest fungus vinegar.

[0026] Figure 13 The figure for the change of α-glucosidase inhibition rate in the fermentation process of black-skin chicken nest fungus vinegar.

[0027] Figure 14 The figure for the change of cholesterol removal rate in the fermentation process of black-skin chicken nest fungus vinegar.

[0028] Figure 15 The figure for the change of pancreatic lipase inhibition rate in the fermentation process of black-skin chicken nest fungus vinegar.

[0029] Figure 16 The figure for the change of bile salt hydrolase specific activity in the fermentation process of black-skin chicken nest fungus vinegar. DETAILED DESCRIPTION

[0030] The application will be described in detail below with reference to the drawings and specific examples, but should not be understood as limiting the application. If not specifically stated, the technical means used in the following examples are conventional means familiar to those skilled in the art, and the materials, reagents, etc. used in the following examples, if not specifically stated, can be obtained from commercial channels.

[0031] Example 1 I. Isolation and identification of acetic acid bacteria

[0032] 1. Isolation and purification of acetic acid bacteria: The acetic acid bacteria strain was obtained by screening from the vinegar dregs in the solid-state vinegar brewing process. Five samples were combined into one at the center and four corners of the fermentation cylinder at 25-30 cm on the 0th day, 7th day, 10th day and 12th day of fermentation, and stored in a self-sealing bag for standby. 10 g of vinegar dregs of different fermentation days were soaked in a conical flask containing 90 mL of sterile water, 35°C, 180 r / min shaking culture for 6 h. Then it was gradiently diluted by 10 1 , 10 2 , 10 3 , 10 4 , 10 5 , 10 6 , 10 7 times, and 100 μL of each was taken and inoculated on GYD medium under aerobic conditions at 35°C for 48 h, and single colonies with transparent halos were picked and inoculated again on GYD medium to isolate and purify the strain.

[0033] GYD medium configuration: take 1 g of yeast extract, 1 g of glucose, 2.5 g of calcium carbonate, and 2 mL of absolute ethanol, and then add water to make up to 100 mL to obtain 100 mL of GYD solid medium. The GYD liquid medium does not add agar.

[0034] 2. Morphological observation of acetic acid bacteria: the purified strain was streaked on a plate and cultured for 48 h. Then a single colony was picked and inoculated into 50 mL of GYD liquid medium, and cultured at 35°C and 120 r / min for 24 h. 50 μL of the bacterial solution was dropped on a clean and dry glass slide, stained with a gram staining kit, dried, and then observed under an optical microscope. The morphologies of the two strains obtained by screening are shown in Figure 1 and Figure 2 .

[0035] 3. Molecular identification of acetic acid bacteria: the bacterial solution was centrifuged at 10,000 r / min and 4°C for 10 min, and the supernatant was discarded. The bacterial pellet was dissolved in 2 mL of EP tube with sterile water, and then sent to Shanghai Biosciences for 16s rDNA sequencing. The two strains obtained were identified as Acetobacter pasteurianus (d739) and Acetobacter fruiticicola (d1042). Acetobacter pasteurianus . Acetobacter pomorum

[0036] II. Fermentation of black chicken nest fungus vinegar.

[0037] 1. Preparation of seed liquid of bacterial strain: Acetobacter pasteurianus d739 and Acetobacter fruiticicola d1042 were inoculated into 50 mL of GYD broth medium, respectively, and cultured at 35°C for 24 h to obtain mother liquor. Before the acetic acid fermentation stage, the mother liquor of the two strains of acetic acid bacteria was inoculated into 500 mL of GYD broth medium at a volume fraction of 2%, and cultured at 35°C for 24 h to obtain seed liquid.

[0038] GYD broth medium configuration: 1 g of yeast extract and 1 g of glucose were dissolved in water, 2 mL of absolute ethanol was added, and then water was added to make up to 100 mL to obtain 100 mL of GYD broth medium.

[0039] Preparation of black chicken nest fungus stock solution: dried black chicken nest fungus was ground into powder with a tissue grinder, and then passed through a 45-mesh sieve. The black chicken nest fungus powder was mixed with distilled water at a mass-volume ratio of 1 g:20 mL, the soluble solid content was determined, and then white granulated sugar was added to adjust the sugar degree to 18°Brix. The mixture was sterilized at 121°C for 20 min, and then cooled to room temperature to obtain the black chicken nest fungus stock solution.

[0040] Yeast solution configuration: 1 g of yeast powder (Angel Yeast Co., Ltd.) was dissolved in 100 mL of sterile water.

[0041] ​2. Brewing of Black-skinned Chicken Mushroom Vinegar: A liquid-segmented fermentation method is used. 2.5% (v / v) of Daqu (Shanxi Rongxin Brewing Co., Ltd.) and 2% (v / v) of yeast liquid are added to the original black-skinned chicken mushroom liquid. After thorough mixing, fermentation is carried out at 28℃ and 180 rpm for 8 days. Subsequently, distilled water is added to the fermentation liquid to adjust the alcohol content to a uniform 5g / 100mL, and then 25% (v / v) of seed liquid is added. CK The mixture was fermented with 25% water (by volume) at 35°C at 180 rpm until the acidity reached 5% and the alcohol content fell below 1%. Samples were taken on days 0, 8, and 16 of fermentation. Finally, the fermented black-skinned chicken mushroom vinegar was filtered to remove residue, sterilized at 121°C for 10 minutes, and then cooled for storage. A. pasteurianus d739 The seed culture for this group was *Acetobacter pasteurellis* d739 seed culture. A. pomorum dl042 The seed culture for this group was *Acetobacter flavum* d1042 seed culture. A. Mix The seed culture of the group was a mixture of equal volumes of Acetobacter pasteurellosis d739 seed culture and Acetobacter fructus d1042 seed culture, with a live bacteria ratio of 1:1.

[0042] III. Sample Testing.

[0043] 1. Sugar content determination: The sugar content of the sample is determined by a saccharimeter. The fermentation broth is mixed and dropped into the detection area of ​​the saccharimeter. After the reading stabilizes, the value is counted, which is the sugar content value of the fermentation broth.

[0044] 2. Alcohol content determination: The fermentation broth was placed in a rotary evaporator for vacuum distillation, with the temperature set at 75℃ and the pressure at 0.08MPa. The distillate was measured using an alcohol meter, and the reading is the alcohol content of the fermentation broth.

[0045] 3. pH value measurement: Insert the calibrated pH meter probe into the fermentation broth to be tested, and record the value after the reading stabilizes. This value is the pH value of the fermentation broth.

[0046] 4. Determination of total acid content: The total acid content in the fermentation broth was determined by acid-base titration.

[0047] 5. Determination of total phenols and total flavonoids: The total phenol content was determined using the Folin-Ciocateu colorimetric method. Gallic acid was used as the standard, and a standard curve was plotted as y = 2.1071x - 0.0002, R0. 2 =0.9991, calculate the total phenol content in black chicken mushroom vinegar according to the formula, where y is the absorbance at 760nm and x is the total phenol content in black chicken mushroom vinegar.

[0048] The total flavonoid content was determined using rutin as a standard, with absorbance measured at 510 nm. A regression equation was established based on the measured values, and a standard curve was plotted as y = 0.5857x - 0.0024, R0. 2=0.9992, the total flavonoids content in black chicken mushroom vinegar was calculated according to the formula, y is the absorbance at 510 nm, and x is the total flavonoids content in black chicken mushroom vinegar.

[0049] 6. Antioxidant activity determination: The antioxidant activity was evaluated by determining the iron ion reducing power, DPPH free radical scavenging rate and ABTS free radical scavenging rate of the sample. The iron ion reducing power was determined by the FRAP method, with FeSO4 as the standard, and the standard curve was y = 1.1393x-0.0053, R 2 =0.9993, the iron ion reducing power of black chicken mushroom vinegar was calculated, y is the absorbance value at 593 nm. The DPPH free radical scavenging rate of black chicken mushroom vinegar was calculated by determining the absorbance of the sample at 517 nm after adding DPPH working solution. The ABTS free radical scavenging rate of black chicken mushroom vinegar was calculated by determining the absorbance of the sample at 734 nm after adding 1 mL of ABTS working solution.

[0050] 7. In vitro determination of sugar-reducing enzyme activity: The fermentation broth was centrifuged at 6000 r / min at 4°C for 10 min, and the supernatant was reserved for determination of sugar-reducing and lipid-reducing enzyme activity. The ɑ-amylase inhibition rate was determined by iodine test solution colorimetry, and the ɑ-glucosidase inhibition rate was determined by colorimetry.

[0051] 8. The cholesterol content was determined by o-phthaldehyde colorimetry, and the cholesterol removal rate was calculated, and the standard curve was: y = 1.9886x-0.0007, R 2 =0.9997, wherein x represents the concentration of cholesterol standard (mg / mL), and y represents the absorbance at wavelength 550 nm. The inhibition rate of pancreatic lipase was determined by PNPP method.

[0052] The bile salt hydrolase enzyme activity and protein content were determined, and glycine was used as the standard to draw the standard curve equation y = 0.203x-0.0015, R 2 =0.9994, y represents the absorbance of the sample at 550 nm, and x represents the bile salt hydrolase enzyme activity of the sample. The protein content was determined by Coomassie brilliant blue G250 method, and the standard curve equation was used to calculate the protein concentration, y = 7.06x+0.0083, R 2 =0.9995, wherein x is the protein concentration (mg / mL), and y is the absorbance at wavelength 595 nm. The specific activity of bile salt hydrolase was calculated according to the formula: specific activity of bile salt hydrolase (U / mg) = bile salt hydrolase enzyme activity (U / mL) / protein concentration (mg / mL).

[0053] Four, experimental results.

[0054] According to Figure 3As shown, the sugar content of the fermentation broth decreased significantly with fermentation time. The initial sugar content was 18°Brix, and the sugar content decreased significantly after 8 days. A. Mix The sugar content decreased to 8.66°Brix, and further decreased to 7.13°Brix after 16 days, indicating that the synergistic effect of yeast and acetic acid bacteria accelerated sugar consumption. Figure 5 As shown, the alcohol content increased to 7.26%, 7.51%, and 7.93% respectively in the early stage due to yeast fermentation, but dropped back in the later stage as acetic acid bacteria converted ethanol into acetic acid. Figure 6 As shown, total acidity increases significantly with fermentation time. A. pasteurianus d739、 A. pomorum dl042 , A. Mix The total acid levels reached 5.19 g / 100 mL, 5.06 g / 100 mL, and 6.24 g / 100 mL at 16 days, respectively. Figure 4 As shown, the pH value continues to decrease due to the accumulation of total acid. A. Mix The pH dropped to 3.23 after 16 days. Compared with the absence of acetic acid bacteria, the addition of acetic acid bacteria significantly accelerated the acidification process, and the mixed strains showed the best performance in terms of sugar utilization and acid production efficiency.

[0055] During fermentation, the total phenolic and total flavonoid contents of *Termitomyces albuminosus* exhibit dynamic changes. Figure 7 In the fermentation process, the total phenol content increased significantly with time. A. Mix The most outstanding performance was observed, reaching 1.32 mg / mL on day 16 of fermentation. Figure 8 In the study, the trend of total flavonoid content was similar to that of total phenols, but the increase was more significant. A. Mix It reached 0.9 mg / mL on day 16, a fourfold increase from day 0. Overall, A. Mix The synergistic effect of multiple bacteria is superior to that of a single bacterial species in both indicators.

[0056] Figure 9 The results showed that the reducing power of iron ions increased significantly with fermentation time. A. pasteurianus d739 , A. pomorum dl042 , A. Mix The reducing power of iron ions was 2.53%, 2.59%, and 2.65% at 16 days. Figure 10 The results show that the DPPH free radical scavenging rate exhibits a two-stage change. A. pasteurianus d739 , A. pomorum dl042 , A. Mix The clearance rate reached 70.05%, 74.12%, and 75.27% after 8 days, a 1.5-fold increase compared to day 0. At day 16, the clearance rate slightly improved. A. Mix The clearance rate was the highest, at 85.54%. Figure 11 The results show that the ABTS free radical scavenging rate continues to rise. A. Mix The clearance rate was the highest, reaching 92.14% at 16 days.

[0057] In the fermentation process of black chicken mushroom vinegar, the change trend of α-amylase inhibition rate and α-glucosidase inhibition rate is as shown in Figure 12 and Figure 13 In the fermentation process of black chicken mushroom vinegar, the change trend of α-amylase inhibition rate and α-glucosidase inhibition rate is as shown in Figure 12 In the fermentation process of black chicken mushroom vinegar, the change trend of α-amylase inhibition rate and α-glucosidase inhibition rate is as shown in A. pasteurianus d739 , A. pomorum dl042 , A. Mix The inhibition rate is 78.21%, 84.8%, 86.79% at 16 days, which is about 4 times higher than that at 0 days, and Figure 13 In the fermentation process of black chicken mushroom vinegar, the change trend of α-amylase inhibition rate and α-glucosidase inhibition rate is as shown in A. pasteurianus d739 , A. pomorum dl042 , A. Mix The inhibition rate is 75.66%, 81.17%, 83.45% at 16 days, which is 3.5 times higher than that at 0 days. Overall, the synergistic effect of the acidification environment and the mixed strains in the later fermentation period significantly enhances the inhibition effect of the two enzymes, especially in the α-amylase inhibition rate.

[0058] As can be seen from Figure 14 , the cholesterol removal rate significantly increases with the fermentation time, A. pasteurianus d739 , A. pomorum dl042 , A. Mix The removal rate is 64.71%, 67.57%, 75.53% at 16 days, mainly due to the acid production of acetic acid bacteria to accelerate cholesterol metabolism. As can be seen from Figure 15 , the pancreatic lipase inhibition rate shows an upward trend, A. pasteurianus d739 , A. pomorum dl042 , A. Mix The inhibition rate is 74.59%, 72.66%, 89.55% at 16 days, which is more than 3 times higher than that at 0 days. As can be seen from Figure 16 , the specific activity of bile salt hydrolase significantly increases in the later fermentation period, A. pasteurianus d739 , A. pomorum dl042 , A. Mix The specific activity is 5.11 U / mg, 5.10 U / mg, 5.26 U / mg at 16 days, indicating that the synergistic effect of acetic acid bacteria and yeast activates enzyme expression through acidification environment, promotes bile salt hydrolysis and cholesterol degradation; overall, the mixed strains perform best in the lipid regulation index.

[0059] It should be noted that when the present application claims involve numerical ranges, both endpoints of each numerical range and any number between the two endpoints can be selected. In order to prevent repetition, the present application describes preferred embodiments.

[0060] While the preferred embodiments of the application have been described, additional variations and modifications can be made to these embodiments by those skilled in the art once they have the benefit of the present disclosure without departing from the spirit and scope of the application. Accordingly, it is intended that such additions and modifications be included within the scope of the application. It is the following claims, including any amendments thereto, which define the scope of the application.

[0061] Obviously, numerous modifications and variations of the present application are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, and their equivalents, the application can be practiced otherwise than as specifically described.

Claims

1. A compound acetic acid bacteria agent, characterized in that, Its active ingredients are *Acetobacter pasteurellii* d739 and *Acetobacter fructus* d1042, wherein *Acetobacter pasteurellii* d739 is classified and named... Acetobacter pasteurianus The *Acetobacter d1042* strain described herein is deposited at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 34004 and a deposit date of March 28, 2025. Acetobacter pomorum The compound acetic acid bacteria agent is deposited at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 34005 and deposit date of March 28, 2025. The ratio of viable bacteria of *Acetobacter pastoris* d739 to *Acetobacter fructus* d1042 in the compound acetic acid bacteria agent is 0.5~1.5:0.5~1.

5.

2. The method for preparing the compound acetic acid bacteria agent according to claim 1, characterized in that, Includes the following steps: Pasteurella acetic acid bacteria d739 and fruit acetic acid bacteria d1042 were inoculated into the culture medium and cultured to obtain Pasteurella acetic acid bacteria d739 bacterial solution and fruit acetic acid bacteria d1042 bacterial solution respectively. The Pasteurella acetic acid bacteria d739 bacterial solution and fruit acetic acid bacteria d1042 bacterial solution were mixed in equal volume ratio to obtain a compound acetic acid bacteria agent.

3. The black-skinned chicken mushroom vinegar prepared by the compound acetic acid bacteria agent according to claim 1 is characterized in that, The preparation steps of the black-skinned chicken mushroom vinegar are as follows: S1. Mix black-skinned chicken mushroom powder with water at a mass-volume ratio of 0.5~1.5g:15~25mL, add white sugar to adjust the sugar content to 15~20°Brix, and sterilize to obtain black-skinned chicken mushroom stock solution; S2. Dissolve 0.5~1.5g of yeast powder in 95~105mL of water to obtain yeast liquid. Add 2%~3% of Daqu (a type of starter culture) and 1%~3% of yeast liquid to the original black chicken mushroom liquid. After mixing, ferment at 25~30℃ and 150~200r / min for 7~9 days to obtain fermentation liquid. S3. Adjust the alcohol content of the fermentation broth to 0.01~0.1g / mL, add 20%~30% of compound acetic acid bacteria agent by volume, and take the acidity as 4%~6% and the alcohol content as 0.5%~1.5% as the fermentation endpoint. Ferment at 32~37℃ and 150~200r / min until the endpoint is reached to obtain black-skinned chicken mushroom vinegar.

4. The application of the compound acetic acid bacteria agent according to claim 1 in the preparation of black-skinned chicken mushroom vinegar.

5. The application of the compound acetic acid bacteria agent according to claim 4 in the preparation of black-skinned chicken mushroom vinegar, characterized in that, The compound acetic acid bacteria agent is used to increase the content of total phenols, total flavonoids and total acids in black-skinned chicken mushroom vinegar.

6. The application of the compound acetic acid bacteria agent according to claim 4 in the preparation of black-skinned chicken mushroom vinegar, characterized in that, The compound acetic acid bacteria agent is used to enhance the antioxidant, hypoglycemic, and lipid-lowering effects of black-skinned chicken mushroom vinegar.

7. The application of the compound acetic acid bacteria agent according to claim 6 in the preparation of black-skinned chicken mushroom vinegar, characterized in that, The antioxidant effects of the black-skinned chicken mushroom vinegar include increasing the reducing power of iron ions, the DPPH free radical scavenging rate, and the ABTS free radical scavenging rate.

8. The application of the compound acetic acid bacteria agent according to claim 6 in the preparation of black-skinned chicken mushroom vinegar, characterized in that, The improvement of the hypoglycemic effect of black-skinned chicken mushroom vinegar includes increasing the inhibition rate of α-amylase and α-glucosidase.

9. The application of the compound acetic acid bacteria agent according to claim 6 in the preparation of black-skinned chicken mushroom vinegar, characterized in that, The improved lipid-lowering effects of black-skinned chicken mushroom vinegar include increasing cholesterol removal rate, pancreatic lipase inhibition rate, and bile salt hydrolase specific enzyme activity.

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