A culture medium for culturing Eurotium cristatum and its application

Abstract

The present invention discloses a culture medium for culturing Eurotium cristatum and its application. Based on each liter of water, the culture medium comprises the following components: 2 - 20 g of corn steep liquor dry powder, 2 - 10 g of β-cyclodextrin, 5 - 20 g of glucose, 5 - 30 g of soluble starch, 0.1 - 1.5 g of magnesium sulfate, and 0.1 - 1.5 g of potassium dihydrogen phosphate. A method for fermenting and producing Fuzhuan tea comprises the following steps: A. Strain culture: inoculating the Eurotium cristatum SHBCC D15081 strain into the aforementioned culture medium and performing shake flask culture to obtain a fermentation culture solution; B. Tea fermentation: uniformly inoculating the fermentation culture solution obtained in step A onto tea leaves and performing fermentation to produce Fuzhuan tea. The culture medium can accelerate the growth rate of Eurotium cristatum and improve its adaptability during the process of fermenting and producing Fuzhuan tea.

Description

Technical Field

[0001] The present invention relates to the technical field of fermentation engineering, and particularly relates to a culture medium for culturing Aspergillus cristatus and its application. Background Art

[0002] Aspergillus cristatus is an edible and medicinal fungus of great significance during the fermentation process of dark tea, especially Fuzhuan tea. Generally, the quality and quantity of the growth of Aspergillus cristatus are regarded as one of the important indicators for evaluating the quality of dark teas such as Fuzhuan tea.

[0003] In the traditional production of Fuzhuan tea, natural fermentation is carried out using Aspergillus cristatus in the environment as the strain. It usually takes a relatively long period (generally 10 - 15 days) to reach an ideal growth density. This will limit the production capacity and production efficiency during large-scale industrial production. Moreover, natural fermentation has the following drawbacks: with the change of the external environment, when the content of other microorganisms in the surrounding area is high, Aspergillus cristatus cannot become the dominant organism, resulting in the failure of flower formation and the mildew of the product; the microorganisms brought into the fermentation from the natural environment can produce mycotoxins, posing potential food safety hazards; the composition of the fermentation microorganisms is complex, resulting in uncontrollable product quality, unstable components, and the inability to guarantee the efficacy and sensory quality; correspondingly, the production cycle and others are not fixed, causing waste of production capacity.

[0004] To solve the above problems, existing research has begun to turn to the isolation and purification of Aspergillus cristatus strains, and specific purified strains are introduced into the fermentation process of tea to improve product quality. However, the current scientific research on the existing Aspergillus cristatus fermentation process is relatively less compared to the research on other widely used fermentation fungi. If the applied strain has a slow growth rate and poor environmental adaptability, not only will a large amount of resources be wasted in the early stage of strain cultivation, but also the industrial production cycle of tea fermentation will be extended, resulting in an increase in production costs.

[0005] Therefore, developing a culture medium suitable for the rapid cultivation of Aspergillus cristatus and a supporting standardized fermentation process is of great significance for improving production efficiency and reducing product production costs. Summary of the Invention

[0006] To solve the above technical problems, the present invention first proposes a culture medium for culturing Aspergillus cristatus, which can accelerate the growth rate of Aspergillus cristatus and improve its adaptability during the fermentation process of producing Fuzhuan tea.

[0007] The present invention also proposes a method for fermenting and producing Fuzhuan tea, which can significantly shorten the fermentation cycle of tea while reducing the inoculation amount of Aspergillus cristatus strain, and is beneficial to improving economic benefits.

[0008] To achieve the above object, the technical solutions adopted by the present invention are as follows:

[0009] Based on the first aspect of the present invention, firstly, a culture medium for Eurotium cristatum is provided, which includes the following components based on per liter of water:

[0010] 2 - 20 g of dry corn steep liquor, 2 - 10 g of β-cyclodextrin, 5 - 20 g of glucose, 5 - 30 g of soluble starch, 0.1 - 1.5 g of magnesium sulfate, and 0.1 - 1.5 g of potassium dihydrogen phosphate.

[0011] In some preferred examples, the pH of the culture medium is 4.0 - 7.0.

[0012] In some preferred examples, the pH of the culture medium is 5.0 - 6.5.

[0013] In some preferred examples, the culture medium is a solid culture medium or a liquid culture medium; when adjusting the culture medium to a solid culture medium, the culture medium composition further includes 10 - 40 g of agar.

[0014] The inventor of the present invention found in continuous research that culturing Eurotium cristatum with the aforementioned culture medium can accelerate the growth of the strain. Especially when the obtained fermentation broth is mixed and fermented with tea leaves, it can significantly promote the fermentation process of tea leaves, and efficient fermentation of Fuzhuan tea can be carried out at a lower inoculation rate.

[0015] It should be noted that in the foregoing culture medium components of the present invention, corn steep liquor powder can provide rich and high-quality nitrogen sources for Eurotium cristatum, and it also contains various vitamins (such as vitamin B group, etc.) and growth factors and other nutrients, which are speculated to have special activation and promotion effects on certain key metabolic pathways of Eurotium cristatum, thus being beneficial to improving its growth ability in the complex environment of tea. However, based on per liter of water, the dosage of corn steep liquor powder is not suitable to be higher than 20 g, otherwise it will instead show a trend of inhibiting the growth of Eurotium cristatum. In addition, β-cyclodextrin has a unique cyclic structure and the ability to selectively form inclusion compounds with small molecules. This inclusion effect is speculated to change the release rate and existence form of nutrients in the culture medium, making it more beneficial for Eurotium cristatum to absorb and utilize nutrients during the tea fermentation process, and at the same time having an interfering effect on the nutrient acquisition of other miscellaneous bacteria, inhibiting the growth of miscellaneous bacteria. However, it is found that the dosage of β-cyclodextrin is not suitable to be higher than 10 g. In addition, glucose, as the main carbon source, provides energy for the growth of Eurotium cristatum; soluble starch, as a supplementary carbon source, can promote the growth and reproduction of Eurotium cristatum. The magnesium ions provided by magnesium sulfate are activators of various enzymes of Eurotium cristatum (such as some enzymes involved in RNA polymerization, etc.). During the tea fermentation process, the presence of magnesium ions can ensure the efficient operation of the enzyme system of Eurotium cristatum, enabling Eurotium cristatum to better decompose the components in tea to obtain nutrients, thereby accelerating the growth rate. Potassium dihydrogen phosphate mainly plays a role in regulating the pH value in the culture medium, maintaining the pH value of the culture medium within a relatively stable range suitable for the growth of Eurotium cristatum. The synergistic combination of the above formulas can produce a specific selective enrichment effect on Eurotium cristatum, shorten the strain culture cycle, and improve the growth promotion effect on Eurotium cristatum during the tea fermentation process, thereby shortening the flowering cycle and improving the quality of tea.

[0016] Based on the second aspect of the present invention, there is also provided a method for fermenting and producing Fuzhuan tea, comprising the following steps:

[0017] A. Strain culture: Inoculate the Eurotium cristatum SHBCC D15081 strain in the culture medium described above, and perform shake flask culture to obtain a fermentation culture solution;

[0018] B. Tea fermentation: Uniformly inoculate the fermentation culture solution obtained in step A onto the tea, and perform fermentation to produce Fuzhuan tea.

[0019] As a preferred process condition, during the shake flask culture process in step A, control the colony number in the obtained fermentation culture solution to be 70 - 90 CFU / ml.

[0020] As a preferred process condition, the conditions for shake flask culture in step A are: temperature 25 - 28 °C, shaker speed 180 - 210 rpm / min, and culture for 80 - 120 h.

[0021] As a preferred process condition, the strain cultivation in step A includes at least one liquid shake flask cultivation. The strain can be directly inoculated into the liquid medium for shake flask cultivation, or the conventional method of first performing solid plate cultivation and then inoculating into the liquid medium for shake flask cultivation can be adopted, and no further limitation is imposed thereon. When solid plate cultivation is required, the solid medium used preferably contains an additional 10 - 40 g of agar per liter of water based on the medium described above.

[0022] As a preferred process condition, in step B, the fermentation broth obtained in step A is mixed and fermented with tea leaves at an inoculation amount of 500 - 800 CFU / g of tea leaves.

[0023] As a preferred process condition, the specific process of the tea leaf fermentation includes:

[0024] S1. Rehydration process: Soak the tea leaves in pure water for 1 - 2 h to allow them to fully absorb water; preferably, the environmental temperature is controlled at 25 - 30 °C during this process.

[0025] S2. Pre - fermentation process: Place the rehydrated tea leaves in a fermentation chamber, control the temperature at 25 - 30 °C, adjust the humidity to 70 - 80%, and pre - ferment for 6 - 8 h.

[0026] S3. Sterilization process: Sterilize the tea leaves with high - temperature steam, set the temperature at 100 - 120 °C, and process for 15 - 20 min.

[0027] S4. Steam - steaming process: Steam - steam the tea leaves in a steamer for 15 - 20 min, and the steam - steaming temperature is 100 - 110 °C.

[0028] S5. Inoculation process: Inoculate the fermentation broth of Eurotium cristatum on the tea leaves and mix evenly; cool the tea leaves to below 40 °C before inoculation.

[0029] S6. Tea - brick pressing process: Press the mixed tea leaves into tea bricks through a mold.

[0030] S7. Film - wrapping process: Wrap the tea bricks tightly with food - grade plastic wrap.

[0031] S8. First flower - forming process: Place the film - wrapped tea bricks in a flower - forming chamber, keep the temperature at 28 - 30 °C, adjust the humidity to 80 - 85%, and ferment for 2 - 4 days.

[0032] S9. Secondary Florets Formation Process: Transfer the tea bricks that have undergone the first florets formation to another florets formation chamber, lower the temperature to 26 - 28 °C, maintain the humidity at 75 - 80%, and ferment for another 2 - 3 days. Through the two florets formation processes with different control conditions, not only the rapid growth and reproduction of Eurotium cristatum are promoted, forming golden "florets" on the tea surface, but also the catechins with astringency in dark tea are decomposed and transformed into substances such as theafulvin with a more mellow flavor, thereby improving the tea quality.

[0033] S10. Drying Process: Dry the fermented tea at 50 - 60 °C until the moisture content of the tea is 5 - 8%.

[0034] As a preferred process condition, the tea is dark tea.

[0035] Through the fermentation method of the present invention, it is possible to obtain a number of florets of 1100×10 3 CFU / g tea or more in the shortest 4 days, the total number of other molds and bacteria is less than 120 CFU / g tea, the catechin content is lower than 5.2 mg / g, and the total amount of theafulvin, theaflavin, and thearubigin is higher than 12.5 mg / g. Specific Embodiments

[0036] The following further illustrates the present invention through specific examples. The examples described in the present invention are only for the illustration of the present invention and do not limit the scope of the present invention.

[0037] In the following examples of the present invention, raw materials and reagents can be obtained through commercial channels without special instructions.

[0038] The analysis and testing means adopted in the following embodiments of the present invention are:

[0039] (1) Number of Bacterial Strains

[0040] Plate Counting Method: Gradiently dilute 1 ml of the fermentation culture solution with sterile physiological saline by an appropriate volume multiple (such as 10 -1 , 10 -2 , 10 -3 etc.) to ensure that the number of colonies on the subsequent plates is moderate for counting; Take a quantitative dilution solution and evenly spread it on the solid medium provided by the present invention, incubate it at a constant temperature of 28 °C, and count after the formation of golden colonies. At least three parallel experiments are performed for each group of samples, and the final result is expressed in CFU / ml. The experimental bacterial strain is Eurotium cristatum SHBCC D15081 (from the Shanghai Center for Microbial Preservation).

[0041] (2) Detection of the Number of Florets

[0042] Refer to the method in the national food safety standard "Microbiological examination of foods - Enumeration of moulds and yeasts" GB / T 4789.15-2016 to detect the number of golden colonies (unit: CFU / g tea) at the inner center of Fuzhuan tea.

[0043] (3)Detection of the total number of other moulds and bacteria

[0044] Refer to the method in the national food safety standard "Microbiological examination of foods - Enumeration of aerobic mesophilic bacteria" GB 4789.2-2022 to detect the total number of colonies (unit: CFU / g tea) at the inner center of Fuzhuan tea, and subtract the number of golden colonies under the same unit. The result is the total number of other moulds and bacteria.

[0045] (4)Determination of catechin content

[0046] Grind the Fuzhuan tea sample into powder, use ethanol as the solvent, dissolve it by ultrasonic wave, and analyze the catechin content by high performance liquid chromatography.

[0047] (5)Determination of the content of tea pigments

[0048] Grind the Fuzhuan tea sample into powder, dissolve it in boiling water to obtain the tea soup, and analyze the total content of tea brown pigment, tea red pigment and tea yellow pigment by spectrophotometry.

[0049] Prepare different culture media according to the formulas in Examples 1-5 and Comparative Examples 1-3 below:

[0050]

Example 1

[0051] Based on 1 L of water, add 10 g of corn steep liquor dry powder, 5 g of β-cyclodextrin, 20 g of glucose, 20 g of soluble starch, 0.5 g of magnesium sulfate, and 0.5 g of potassium dihydrogen phosphate, and adjust the pH to 5.5 to obtain Culture Medium A.

[0052]

Example 2

[0053] Based on 1 L of water, add 5 g of corn steep liquor dry powder, 10 g of β-cyclodextrin, 5 g of glucose, 30 g of soluble starch, 0.1 g of magnesium sulfate, and 1.5 g of potassium dihydrogen phosphate, and adjust the pH to 6.5 to obtain Culture Medium B.

[0054]

Example 3

[0055] Based on 1 L of water, add 2 g of corn steep liquor dry powder, 10 g of β-cyclodextrin, 20 g of glucose, 5 g of soluble starch, 1.5 g of magnesium sulfate, and 0.1 g of potassium dihydrogen phosphate, and adjust the pH to 5.0 to obtain Culture Medium C.

[0056]

Example 4

[0057] Per liter of water, add 15 g of corn steep liquor dry powder, 4 g of β-cyclodextrin, 10 g of glucose, 15 g of soluble starch, 1.0 g of magnesium sulfate, and 0.5 g of potassium dihydrogen phosphate, and adjust the pH to 6.0 to obtain medium D.

[0058]

Example 5

[0059] Per liter of water, add 20 g of corn steep liquor dry powder, 2 g of β-cyclodextrin, 15 g of glucose, 25 g of soluble starch, 0.5 g of magnesium sulfate, and 1.0 g of potassium dihydrogen phosphate, and adjust the pH to 5.5 to obtain medium E.

[0060]

Comparative Example 1

[0061] Prepare medium F with a formulation basically the same as that in Example 1, except that corn steep liquor dry powder is not added.

[0062]

Comparative Example 2

[0063] Prepare medium G with a formulation basically the same as that in Example 1, except that β-cyclodextrin is not added.

[0064]

Comparative Example 3

[0065] Prepare liquid medium H according to the following formulation:

[0066] Per liter of water, 20 g of glucose, 20 g of maltose, 1 g of yeast extract, and adjust the pH to 5.5.

[0067] Ferment tea leaves according to the methods in the following Application Examples 1-5 and Comparative Application Examples 1-3 respectively:

[0068]

Application Example 1

[0069] Perform tea leaf fermentation (dark green tea) according to the following process:

[0070] S1. Rehydration process: Soak the tea leaves in pure water at 25°C for 2 h to allow them to fully absorb water;

[0071] S2. Pre-fermentation process: Place the rehydrated tea leaves in a fermentation chamber, control the temperature at 30°C, adjust the humidity to 70%, and pre-ferment for 7 h;

[0072] S3. Sterilization process: Sterilize the tea leaves with high-temperature steam, set the temperature at 120°C, and process for 20 min;

[0073] S4. Steam distillation process: Place the tea leaves in a steamer and steam distill for 15 min, with the steam distillation temperature at 110°C;

[0074] S5. Inoculation process: Inoculate the Eurotium cristatum SHBCC D15081 strain in the autoclaved medium A, and culture it in a shaking flask at 25°C and 180 rpm / min for 80 h until the colony count reaches 75 CFU / ml to obtain the fermentation broth; then mix and ferment the fermentation broth of the Eurotium cristatum strain with the tea leaves at an inoculation amount of 500 CFU / g of tea leaves.

[0075] S6. Tea brick pressing process: Press the mixed tea leaves into tea bricks through a mold.

[0076] S7. Film wrapping process: Wrap the tea bricks tightly with food-grade plastic wrap.

[0077] S8. First flower-forming process: Place the film-wrapped tea bricks in a flower-forming chamber, keep the temperature at 28°C, adjust the humidity to 85%, and ferment for 3 days.

[0078] S9. Second flower-forming process: Transfer the tea bricks that have undergone the first flower-forming to another flower-forming chamber, lower the temperature to 26°C, maintain the humidity at 80%, and ferment for another 2 days.

[0079] S10. Drying process: Dry the fermented tea leaves at 50°C until the moisture content of the tea leaves is 5 - 8% to obtain Fuzhuan tea.

[0080]

Application Example 2

[0081] Ferment the tea leaves (dark green tea) according to the following process:

[0082] S1. Rehydration process: Soak the tea leaves in pure water at 30°C for 1 h to allow them to fully absorb water.

[0083] S2. Pre-fermentation process: Place the rehydrated tea leaves in a fermentation chamber, control the temperature at 28°C, adjust the humidity to 80%, and pre-ferment for 6 h.

[0084] S3. Sterilization process: Sterilize the tea leaves with high-temperature steam, set the temperature at 100°C, and process for 15 min.

[0085] S4. Steam distillation process: Steam-distill the tea leaves in a steamer for 20 min, and the steam-distillation temperature is 100°C.

[0086] S5. Inoculation process: Inoculate the Eurotium cristatum SHBCC D15081 strain in the autoclaved medium B, and culture it in a shaking flask at 28°C and 210 rpm / min for 120 h until the colony count reaches 70 CFU / ml to obtain the fermentation broth; then mix and ferment the fermentation broth of the Eurotium cristatum strain with the tea leaves at an inoculation amount of 800 CFU / g of tea leaves.

[0087] S6, Brick Pressing Process: Press the mixed tea leaves into tea bricks through a mold;

[0088] S7, Film Wrapping Process: Wrap the tea bricks tightly with food-grade plastic wrap;

[0089] S8, First Blooming Process: Put the film-wrapped tea bricks into a blooming room, keep the temperature at 30 °C, adjust the humidity to 85%, and ferment for 2 days;

[0090] S9, Second Blooming Process: Transfer the tea bricks that have undergone the first blooming to another blooming room, lower the temperature to 28 °C, maintain the humidity at 80%, and ferment for another 3 days;

[0091] S10, Drying Process: Dry the fermented tea leaves at 60 °C until the water content of the tea leaves is 5 - 8%, obtaining Fuzhuan tea.

[0092]

Application Example 3

[0093] Ferment the tea leaves (dark green tea) according to the following process:

[0094] S1, Rehydration Process: Soak the tea leaves in pure water at 28 °C for 1.5 h to allow them to fully absorb water;

[0095] S2, Pre-fermentation Process: Place the rehydrated tea leaves in a fermentation room, control the temperature at 25 °C, adjust the humidity to 75%, and pre-ferment for 8 h;

[0096] S3, Sterilization Process: Sterilize the tea leaves with high-temperature steam, set the temperature at 110 °C, and process for 18 min;

[0097] S4, Steam Blanching Process: Steam the tea leaves in a steamer for 18 min, and the steam blanching temperature is 100 °C;

[0098] S5, Inoculation Process: Inoculate the Eurotium cristatum SHBCC D15081 strain in the autoclaved medium C, shake flask culture at 26 °C and 200 rpm / min for 100 h until the colony count reaches 90 CFU / ml to obtain the fermentation broth; then mix and ferment the tea leaves with the fermentation broth of the Eurotium cristatum strain at an inoculation amount of 700 CFU / g of tea leaves;

[0099] S6, Brick Pressing Process: Press the mixed tea leaves into tea bricks through a mold;

[0100] S7, Film Wrapping Process: Wrap the tea bricks tightly with food-grade plastic wrap;

[0101] S8, First Blooming Process: Put the film-wrapped tea bricks into a blooming room, keep the temperature at 29 °C, adjust the humidity to 82%, and ferment for 2 days;

[0102] S9. Secondary flowering process: Transfer the tea bricks that have undergone the first flowering to another flowering chamber, lower the temperature to 27°C, maintain the humidity at 78%, and ferment for another 2 days;

[0103] S10. Drying process: Dry the fermented tea leaves at 60°C until the water content of the tea leaves is 5 - 8%, obtaining Fuzhuan tea.

[0104]

Application Example 4

[0105] Ferment the tea leaves (dark green tea) according to the following process:

[0106] S1. Rehydration process: Soak the tea leaves in pure water at 25°C for 2 h to allow them to fully absorb water;

[0107] S2. Pre-fermentation process: Place the rehydrated tea leaves in a fermentation chamber, control the temperature at 30°C, adjust the humidity to 77%, and pre-ferment for 6.5 h;

[0108] S3. Sterilization process: Sterilize the tea leaves with high-temperature steam, set the temperature at 120°C, and process for 15 min;

[0109] S4. Steam treatment process: Steam the tea leaves in a steamer for 15 min, and the steam temperature is 105°C;

[0110] S5. Inoculation process: Inoculate the Eurotium cristatum SHBCC D15081 strain in the autoclaved medium D, shake-flask culture at 25°C and 200 rpm / min for 110 h until the colony count reaches 80 CFU / ml to obtain the fermentation culture solution; then mix the fermentation culture solution of the Eurotium cristatum strain with the tea leaves according to an inoculation amount of 600 CFU / g of tea leaves for mixed fermentation;

[0111] S6. Tea brick pressing process: Press the mixed tea leaves into tea bricks through a mold;

[0112] S7. Film wrapping process: Wrap the tea bricks tightly with food-grade plastic wrap;

[0113] S8. First flowering process: Place the film-wrapped tea bricks in a flowering chamber, keep the temperature at 28°C, adjust the humidity to 80%, and ferment for 3 days;

[0114] S9. Secondary flowering process: Transfer the tea bricks that have undergone the first flowering to another flowering chamber, lower the temperature to 26°C, maintain the humidity at 75%, and ferment for another 3 days;

[0115] S10. Drying process: Dry the fermented tea leaves at 50°C until the water content of the tea leaves is 5 - 8%, obtaining Fuzhuan tea.

[0116]

Application Example 5

[0117] The tea leaves (dark green tea) are fermented according to the following process:

[0118] S1. Rehydration process: Soak the tea leaves in pure water at 25 - 30 °C for 1 - 2 h to allow them to fully absorb water.

[0119] S2. Pre - fermentation process: Place the rehydrated tea leaves in a fermentation chamber, control the temperature at 25 °C, adjust the humidity to 74%, and pre - ferment for 7 h.

[0120] S3. Sterilization process: Sterilize the tea leaves with high - temperature steam, set the temperature at 100 °C, and process for 20 min.

[0121] S4. Steam - steaming process: Place the tea leaves in a steamer and steam - steam for 20 min, with the steam - steaming temperature at 100 °C.

[0122] S5. Inoculation process: Inoculate the Eurotium cristatum SHBCC D15081 strain in a high - pressure - sterilized medium E, culture in a shaking flask at 28 °C and 180 rpm / min for 90 h until the colony count reaches 90 CFU / ml to obtain a fermentation culture solution; then mix the fermentation culture solution of the Eurotium cristatum strain with the tea leaves according to an inoculation amount of 720 CFU / g of tea leaves for mixed fermentation.

[0123] S6. Brick - pressing process: Press the mixed tea leaves into tea bricks through a mold.

[0124] S7. Film - wrapping process: Wrap the tea bricks tightly with food - grade plastic wrap.

[0125] S8. First flower - forming process: Place the film - wrapped tea bricks in a flower - forming chamber, keep the temperature at 30 °C, adjust the humidity to 85%, and ferment for 2 days.

[0126] S9. Second flower - forming process: Transfer the tea bricks that have undergone the first flower - forming to another flower - forming chamber, lower the temperature to 28 °C, maintain the humidity at 80%, and ferment for another 2 days.

[0127] S10. Drying process: Dry the fermented tea leaves at 55 °C until the water content of the tea leaves is 5 - 8% to obtain Fu - brick tea.

[0128]

Comparative application example 1

[0129] The tea leaves are fermented in a method basically the same as that of application example 1, except that medium A is replaced by medium F.

[0130]

Comparative application example 2

[0131] The tea leaves are fermented in a method basically the same as that of application example 1, except that medium A is replaced by medium G.

[0132]

Comparative Application Example 3

[0133] The tea fermentation was carried out in substantially the same manner as in Application Example 1, except that culture medium A was replaced with culture medium H.

[0134] The number of golden flowers, the total number of other molds and bacteria, the catechin content, and the total amounts of tea brown pigment, theaflavin, and thearubigin in the tea leaves fermented in each application example were analyzed, and the results are shown in Table 1.

[0135] Table 1. Analysis Results

[0136] Number of golden flower CFU / g Total number of other molds and bacteria CFU / g Catechin content mg / g Total amount of theabrownin, theaflavin and thearubigin mg / g Application Example 1 <![CDATA[1200×10 3 > <100 5.2 12.5 Application Example 2 <![CDATA[1180×10 3 > <120 4.8 13.0 Application Example 3 <![CDATA[1150×10 3 > <110 5.0 12.6 Application Example 4 <![CDATA[1250×10 3 > <80 4.9 13.2 Application Example 5 <![CDATA[1100×10 3 > <90 5.1 12.7 Comparative Application Example 1 <![CDATA[400×10 3 > 350 8.2 9.0 Comparative Application Example 2 <![CDATA[500×10 3 > 320 7.9 8.7 Comparative Application Example 3 <![CDATA[180×10 3 > 200 8.7 7.1

[0137] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the method of the present invention, several improvements and supplements can be made, and these improvements and supplements should also be regarded as the protection scope of the present invention.

Claims

1. A method for producing Fuzhuan tea by fermentation, characterized in that: The following steps are involved: A. Bacterial culture: inoculate the SHBCC D15081 strain in a culture medium, culture in a shake flask, and obtain a fermentation culture solution; the culture medium is added with the following components per liter of water: 2-20 g corn steep liquor powder, 2-10 g β-cyclodextrin, 5-20 g glucose, 5-30 g soluble starch, 0.1-1.5 g magnesium sulfate, and 0.1-1.5 g potassium dihydrogen phosphate; B. Tea fermentation: The fermentation culture solution obtained in step A is evenly inoculated onto tea leaves to ferment and produce Fuzhuan tea.

2. The method for producing Fuzhuan tea by fermentation according to claim 1, characterized in that: The pH of the culture medium is 4.0-7.

0.

3. The method for producing Fuzhuan tea by fermentation according to claim 1, characterized in that: The pH of the culture medium is 5.0-6.

5.

4. The method for producing Fuzhuan tea by fermentation according to claim 1, characterized in that: During the shake flask culture process in step A, the colony count in the obtained fermentation culture solution is controlled to be 70-90 CFU / ml.

5. The method for producing Fuzhuan tea by fermentation according to claim 4, characterized in that: The conditions for the shake flask culture in step A are: temperature 25-28° C., shaker speed 180-210 rpm / min, and culture 80-120 h.

6. The method for producing Fuzhuan tea by fermentation according to any one of claims 1 to 5, characterized in that: In step B, the fermentation culture solution obtained in step A is mixed with tea leaves at an inoculation amount of 500-800 CFU / g tea leaves for fermentation.

7. The method for producing Fuzhuan tea by fermentation according to claim 6, characterized in that: The specific process of tea fermentation includes: S1, rehydration process: soak the tea leaves in pure water for 1-2 hours to allow them to fully absorb water; S2, pre-fermentation process: the rehydrated tea leaves are placed in a fermentation room, the temperature is controlled at 25-30°C, the humidity is adjusted to 70-80%, and the pre-fermentation is carried out for 6-8 hours; S3, sterilization process: use high temperature steam to sterilize the tea leaves, the temperature is set to 100-120℃, and the treatment time is 15-20min; S4, steaming process: steam the tea leaves in a steamer for 15-20 minutes at a steaming temperature of 100-110°C; S5, inoculation step: inoculating the fermented culture solution of Eurotium cristatum onto the tea leaves and mixing them evenly; S6, brick pressing process: pressing the mixed tea leaves into tea bricks through a mold; S7, film wrapping process: Use food-grade plastic wrap to wrap the tea brick tightly; S8, first blooming process: put the wrapped tea bricks into the blooming room, keep the temperature at 28-30℃, adjust the humidity to 80-85%, and ferment for 2-4 days; S9, secondary blooming process: transfer the tea bricks that have undergone the first blooming to another blooming room, lower the temperature to 26-28℃, maintain the humidity at 75-80%, and ferment for another 2-3 days; S10, drying process: drying the fermented tea leaves at 50-60°C until the moisture content of the tea leaves is 5-8%.

8. The method for producing Fuzhuan tea by fermentation according to any one of claims 1 to 5, characterized in that: The tea leaves are dark tea.