Black tea preparation process based on microbial fermentation

Abstract

The invention provides a black tea preparation process based on microbial fermentation, which comprises the following steps: (1) selecting fresh tea leaves as raw materials, and naturally withering; (2) rolling the withered fresh leaf raw material, and adding bacillus subtilis and trichoderma reesei bacterial liquid to promote hydrolysis and saccharification of cellulose and crushing of cell walls; (3) immediately adding saccharomyces cerevisiae liquid for fermentation and aroma enhancement after rolling is finished; and (4) after the tea leaves are fermented to red brown, ending the fermentation, performing high-temperature baking, performing cooling, and performing drying at 60-80 DEG C to obtain the black tea with the unique flavor. The quality improvement and aroma enhancement of the black tea are realized by utilizing a microbial fermentation technology. The technology is simple and easy to operate, and the prepared black tea is higher in amino acid content, red and bright in tea soup color, mellow and refreshing in taste, rich in fragrance, fragrant and sweet in taste, weakened in bitter taste and unique in flavor.

Description

Technical Field

[0001] The invention belongs to the field of tea processing, and specifically relates to the technical field of preparation of black tea fermented by microorganisms. Background Art

[0002] Black tea is one of the most consumed tea products in the world. The traditional black tea production process includes withering, rolling, fermentation and drying. The flavor of black tea is affected by many factors, including fresh leaf varieties, picking seasons, growing environment, production process, storage conditions and brewing methods. Among them, the fermentation process is the key link that determines the quality and characteristics of black tea, and is directly related to the characteristic color, aroma and taste of black tea. The black tea produced by traditional natural fermentation has a high content of bitter substances such as tea polyphenols, caffeine, and quinine. The brewed tea soup is bitter and has a strong sour and astringent feeling, which makes some people feel uncomfortable. In addition, the tea produced by traditional natural fermentation often has deficiencies such as insufficient aroma and heavy green taste, which leads to the lack of competitiveness of black tea prepared by traditional processes in the market. Therefore, with the increasing demand of consumers for high-quality black tea, it is particularly important to optimize the black tea fermentation process.

[0003] The main components of black tea include polyphenols, caffeine, protein, fat, sugar, cellulose, carotene, vitamins, amino acids and minerals, etc. Microorganisms produce some enzymes in their own metabolism, such as proteases and cellulases, which can catalyze a series of reactions such as degradation, oxidation and condensation of chemical components such as tea polyphenols, flavonoids and flavonoids, and amino acids during the fermentation of black tea, resulting in a decrease in the content of polyphenols, polysaccharides and flavonoids, and an increase in the content of derivatives such as theabrownin and catechins, thus causing changes in the flavor quality of black tea.

[0004] Based on this, the present invention adds three different food-grade safe probiotics, Trichoderma reesei, Bacillus subtilis and Saccharomyces cerevisiae, in a certain proportion during the fermentation process of black tea, and utilizes a series of enzymes produced by the growth and metabolic activities of microorganisms to promote the transformation of various components of the tea leaves themselves, reduce the bitterness of the tea soup, increase the aroma of the tea soup, and improve the quality of the black tea. Summary of the invention

[0005] In view of the shortcomings of the above-mentioned existing tea fermentation technology, the present invention has improved the traditional tea making process and developed a black tea preparation process based on microbial fermentation. The quality and aroma of tea can be improved by utilizing microbial fermentation technology, and the process flow is optimized by adjusting the proportion of microbial agents, ultimately producing high-quality black tea.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A black tea preparation process based on microbial fermentation, the process comprising the following steps:

[0008] (1) Fresh leaf selection: Pick fresh black tea leaves, remove impurities, select intact and undamaged fresh leaves, and spread them out in a cool and ventilated place;

[0009] (2) Withering: the fresh leaves from step (1) are evenly spread to a thickness of 10-15 cm and withered naturally;

[0010] (3) rolling: placing the tea leaves withered in step (2) into a rolling machine for mechanical rolling or manual rolling, with the rolling pressure being in the order of light-heavy-light, and adding Bacillus subtilis and Trichoderma reesei liquid during the rolling process;

[0011] (4) Microbial fermentation: The tea leaves treated in step (3) are uniformly sprayed with yeast solution, and the tea leaves are immediately wrapped with wet gauze, and the external environment is maintained at 18-35° C. and the humidity is 60-95% for fermentation;

[0012] (5) hot air drying: the tea leaves fermented in step (4) are transferred to a tea aroma machine and dried with hot air at 90-120° C. for 30 min. After cooling, they are dried at 60-80° C. until the moisture content is 5%;

[0013] (6) Screening and packaging: The tea leaves dried in step (5) are screened using a shaking sieve or a floating sieve to remove impurities, and the tea leaves are classified by category and then sealed and packaged.

[0014] Compared with the prior art, the present invention has the following technical advantages:

[0015] (1) Bacillus subtilis and Trichoderma reesei were added during the rolling stage to promote the hydrolysis and saccharification of tea cellulose and the breakage of cell walls, so that the intracellular matrix can penetrate the cell wall more evenly, which is beneficial to the subsequent oxidation and fermentation process.

[0016] (2) Yeast culture liquid is added during the oxidation fermentation process. Through the metabolism of microorganisms themselves, the action of polyphenol oxidase, pectinase, cellulase and other enzymes that play a key role in the fermentation process is enhanced, and the content of amino acids and other substances in the tea itself is increased, thereby improving the quality and aroma of the tea. DETAILED DESCRIPTION

[0017] The present invention is further described in detail below in conjunction with specific implementation modes.

[0018] Bacillus subtilis, Trichoderma Reesei, and Saccharomyces cerevisiae used in this example were purchased from China Industrial Microbiological Culture Collection Center.

[0019] The preparation process of the present invention is applicable to large-leaf black tea as well as medium-leaf black tea and small-leaf black tea. The following mainly describes large-leaf black tea and small-leaf black tea as examples.

[0020] Example 1:

[0021] The black tea is prepared by the following process:

[0022] (1) Selecting tea raw materials: Select large-leaf tea trees from Luchun County, Honghe Prefecture, Yunnan Province, with one bud and two leaves as raw materials, wherein the moisture content of the raw materials is not less than 78%.

[0023] (2) Withering: Spread the fresh leaves in a withering tank at a height of 10-15 cm at 18-35°C. The relative humidity at the beginning of withering is 60-95%. Wither naturally for 4-11 hours until the color of the fresh leaves turns dark green, the leaves are curled and feel soft. At this time, the moisture content of the tea leaves is 60-65%.

[0024] (3) Rolling: Put the withered tea leaves into a rolling machine for gentle rolling for 20-40 minutes, then pressurize and roll for 10-15 minutes. The pressurized cover of the rolling machine is in contact with the tea leaves. Add 2 ml of Bacillus subtilis solution (OD600=1) per 100 grams of tea leaves, and then roll gently for another 20-30 minutes on the rolling machine.

[0025] (4) Fermentation: After the tea leaves are rolled, 6 ml of yeast solution (OD600 = 1) is added to every 100 g of tea leaves. After mixing evenly, the tea leaves are wrapped with wet gauze and fermented at 18-35°C and a relative humidity of 60-95%. During the fermentation process, the pile is turned and water is added. Fermentation is completed when the tea leaves turn reddish brown.

[0026] (5) Drying: Dry the tea leaves at a high temperature of 90-120°C for 30 minutes, cool them down and then dry them at 60-80°C. The moisture content of the dried tea leaves is less than 5%.

[0027] (6) Use hot water at about 97°C to prepare black tea.

[0028] Example 2:

[0029] The black tea is prepared by the following process:

[0030] (1) Selecting tea raw materials: Select large-leaf tea trees from Luchun County, Honghe Prefecture, Yunnan Province, with one bud and two leaves as raw materials, wherein the moisture content of the raw materials is not less than 78%.

[0031] (2) Withering: Spread the fresh leaves in a withering tank at a height of 10-15 cm at 18-35°C. The relative humidity at the beginning of withering is 60-95%. Wither naturally for 4-11 hours until the color of the fresh leaves turns dark green, the leaves are curled and feel soft. At this time, the moisture content of the tea leaves is 60-65%.

[0032] (3) Rolling: Put the withered tea leaves into a rolling machine for gentle rolling for 20-40 minutes, then pressurize and roll for 10-15 minutes. The pressurized cover of the rolling machine is in contact with the tea leaves. Add 2 ml of Bacillus subtilis solution (OD600=1) per 100 grams of tea leaves, and then roll gently for another 20-30 minutes on the rolling machine.

[0033] (4) Fermentation: After the tea leaves are rolled, 3 ml of yeast solution (OD600 = 1) is added to every 100 g of tea leaves. After mixing evenly, the tea leaves are wrapped with wet gauze and fermented at 18-35°C and a relative humidity of 60-95%. During the fermentation process, the pile is turned and water is added. Fermentation is completed when the tea leaves turn reddish brown.

[0034] (5) Drying: Dry the tea leaves at a high temperature of 90-120°C for 30 minutes, cool them down and then dry them at 60-80°C. The moisture content of the dried tea leaves is less than 5%.

[0035] (6) Use hot water at about 97°C to prepare black tea.

[0036] Example 3:

[0037] The black tea is prepared by the following process:

[0038] (1) Selecting tea raw materials: Selecting small-leaf tea trees from Luchun County, Honghe Prefecture, Yunnan Province, with one bud and two leaves as raw materials, wherein the water content of the raw materials is not less than 78%.

[0039] (2) Withering: Spread the fresh leaves in a withering tank at a height of 10-15 cm at 18-35°C. The relative humidity at the beginning of withering is 60-95%. Wither naturally for 4-11 hours until the color of the fresh leaves turns dark green, the leaves are curled and feel soft. At this time, the moisture content of the tea leaves is 60-65%.

[0040] (3) Rolling: Put the withered tea leaves into a rolling machine for gentle rolling for 20-40 minutes, then pressurize and roll for 10-15 minutes. The pressurized cover of the rolling machine is in contact with the tea leaves. Add 2 ml of Bacillus subtilis solution (OD600=1) per 100 grams of tea leaves, and then roll gently for another 20-30 minutes on the rolling machine.

[0041] (4) Fermentation: After the tea leaves are rolled, 3 ml of yeast solution (OD600 = 1) is added to every 100 g of tea leaves. After mixing evenly, the tea leaves are wrapped with wet gauze and fermented at 18-35°C and a relative humidity of 60-95%. During the fermentation process, the pile is turned and water is added. Fermentation is completed when the tea leaves turn reddish brown.

[0042] (5) Drying: Dry the tea leaves at a high temperature of 90-120°C for 30 minutes, cool them down and then dry them at 60-80°C. The moisture content of the dried tea leaves is less than 5%.

[0043] (6) Use hot water at about 97°C to brew black tea.

[0044] Example 4:

[0045] The black tea is prepared by the following process:

[0046] (1) Selecting tea raw materials: Select large-leaf tea trees from Luchun County, Honghe Prefecture, Yunnan Province, with one bud and two leaves as raw materials, wherein the moisture content of the raw materials is not less than 78%.

[0047] (2) Withering: Spread the fresh leaves in a withering tank at a height of 10-15 cm at 18-35°C. The relative humidity at the beginning of withering is 60-95%. Wither naturally for 4-11 hours until the color of the fresh leaves turns dark green, the leaves are curled and feel soft. At this time, the moisture content of the tea leaves is 60-65%.

[0048] (3) Rolling: Put the withered tea leaves into a rolling machine for gentle rolling for 20-40 minutes, then pressurize and roll for 10-15 minutes. The pressurized cover of the rolling machine is in contact with the tea leaves. Add 2 ml of Bacillus subtilis solution (OD600=1) per 100 grams of tea leaves, and then roll gently for another 20-30 minutes on the rolling machine.

[0049] (4) Fermentation: After the tea leaves are rolled, 4 ml of yeast solution (OD600 = 1) is added to every 100 g of tea leaves. After mixing evenly, the tea leaves are wrapped with wet gauze and fermented at 18-35°C and a relative humidity of 60-95%. During the fermentation process, the pile is turned and water is added. Fermentation is completed when the tea leaves turn reddish brown.

[0050] (5) Drying: Dry the tea leaves at a high temperature of 90-120°C for 30 minutes, cool them down and then dry them at 60-80°C. The moisture content of the dried tea leaves is less than 5%.

[0051] (6) Use hot water at about 97°C to brew black tea.

[0052] Example 5:

[0053] The black tea is prepared by the following process:

[0054] (1) Selecting tea raw materials: Selecting small-leaf tea trees from Luchun County, Honghe Prefecture, Yunnan Province, with one bud and two leaves as raw materials, wherein the water content of the raw materials is not less than 78%.

[0055] (2) Withering: Spread the fresh leaves in a withering tank at a height of 15-20 cm at 18-35°C. The relative humidity at the beginning of withering is 60-95%. Wither naturally for 4-11 hours until the color of the fresh leaves turns dark green, the leaves are curled and feel soft. At this time, the moisture content of the tea leaves is 60-65%.

[0056] (3) Rolling: The withered tea leaves are placed in a rolling machine for gentle rolling for 20-40 minutes, and then pressed and rolled for 10-15 minutes. The pressurized cover of the rolling machine is in contact with the tea leaves. 3 ml of Bacillus subtilis solution (OD600 = 1) is added to every 100 grams of tea leaves, and then the rolling machine is gently rolled for another 20-30 minutes.

[0057] (4) Fermentation: After the tea leaves are rolled, 4 ml of yeast solution (OD600 = 1) is added to every 100 g of tea leaves. After mixing evenly, the tea leaves are wrapped with wet gauze and fermented at 18-35°C and a relative humidity of 60-95%. During the fermentation process, the pile is turned and water is added. Fermentation is completed when the tea leaves turn reddish brown.

[0058] (5) Drying: Dry the tea leaves at a high temperature of 90-120°C for 30 minutes, cool them down and then dry them at 60-80°C. The moisture content of the dried tea leaves is less than 5%.

[0059] (6) Use hot water at about 97°C to brew black tea.

[0060] Example 6:

[0061] The black tea is prepared by the following process:

[0062] (1) Selecting tea raw materials: Selecting small-leaf tea trees from Luchun County, Honghe Prefecture, Yunnan Province, with one bud and two leaves as raw materials, wherein the water content of the raw materials is not less than 78%.

[0063] (2) Withering: Spread the fresh leaves in a withering tank at a height of 15-20 cm at 18-35°C. The relative humidity at the beginning of withering is 60-95%. Wither naturally for 4-11 hours until the color of the fresh leaves turns dark green, the leaves are curled and feel soft. At this time, the moisture content of the tea leaves is 60-65%.

[0064] (3) Rolling: The withered tea leaves are placed in a rolling machine for gentle rolling for 20-40 minutes, and then pressed and rolled for 10-15 minutes. The rolling machine is pressed so that the cover is in contact with the tea leaves. The bacterial solution is added at a ratio of 3 ml of Trichoderma reesei suspension (OD600 = 1) per 100 grams of tea leaves, and then the rolling machine is gently rolled for another 20-30 minutes.

[0065] (4) Fermentation: After the tea leaves are rolled, 6 ml of yeast suspension (OD600 = 1) is added to the bacterial solution for every 100 g of tea leaves. After mixing evenly, the tea leaves are wrapped with wet gauze and fermented at 18-35°C and a relative humidity of 60-95%. During the fermentation process, the pile is turned and water is added. The fermentation is completed when the tea leaves turn reddish brown.

[0066] (5) Drying: Dry at 90-120℃ for 30 minutes, cool and then oven dry at 60-80℃. The moisture content of the dried tea leaves is below 5%.

[0067] (6) Use hot water at about 97°C to brew black tea.

[0068] Example 7:

[0069] The black tea is prepared by the following process:

[0070] (1) Selecting tea raw materials: Select large-leaf tea trees from Luchun County, Honghe Prefecture, Yunnan Province, with one bud and two leaves as raw materials, wherein the moisture content of the raw materials is not less than 78%.

[0071] (2) Withering: Spread the fresh leaves in a withering tank at a height of 15-20 cm at 18-35°C. The relative humidity at the beginning of withering is 60-95%. Wither naturally for 4-11 hours until the color of the fresh leaves turns dark green, the leaves are curled and feel soft. At this time, the moisture content of the tea leaves is 60-65%.

[0072] (3) Rolling: The withered tea leaves are placed in a rolling machine for gentle rolling for 20-40 minutes, and then pressed and rolled for 10-15 minutes. The rolling machine is then pressed so that the cover is in contact with the tea leaves. A bacterial solution is added at a ratio of 10 ml of Trichoderma reesei suspension (OD600=1) and 10 ml of Bacillus subtilis (OD600=1) per 100 g of tea leaves, and then gently rolled for another 20-30 minutes on the rolling machine.

[0073] (4) Fermentation: After the tea leaves are rolled, 12 ml of yeast suspension (OD600 = 1) is added to the bacterial solution for every 100 g of tea leaves. After mixing evenly, the tea leaves are wrapped with wet gauze and fermented at 18-35°C and a relative humidity of 60-95%. During the fermentation process, the pile is turned and water is added. The fermentation is completed when the tea leaves turn reddish brown.

[0074] (5) Drying: Dry at 90-120℃ for 30 minutes, cool and then oven dry at 60-80℃. The moisture content of the dried tea leaves is below 5%.

[0075] (6) Use hot water at about 97°C to brew black tea.

[0076] Example 8:

[0077] The black tea is prepared by the following process:

[0078] (1) Selecting tea raw materials: Select large-leaf tea trees from Luchun County, Honghe Prefecture, Yunnan Province, with one bud and two leaves as raw materials, wherein the moisture content of the raw materials is not less than 78%.

[0079] (2) Withering: Spread the fresh leaves in a withering tank at a height of 15-20 cm at 18-35°C. The relative humidity at the beginning of withering is 60-95%. Wither naturally for 4-11 hours until the color of the fresh leaves turns dark green, the leaves are curled and feel soft. At this time, the moisture content of the tea leaves is 60-65%.

[0080] (3) Rolling: The withered tea leaves are placed in a rolling machine for gentle rolling for 20-40 minutes, and then pressed and rolled for 10-15 minutes. The rolling machine is then pressed so that the cover is in contact with the tea leaves. Add 1 ml of Trichoderma reesei suspension (OD600=1) and 1 ml of Bacillus subtilis suspension (OD600=1) per 100 g of tea leaves, and then gently roll for another 20-30 minutes on the rolling machine.

[0081] (4) Fermentation: After the tea leaves are rolled, 1 ml of yeast suspension (OD600 = 1) is added to the tea leaves at a ratio of 1 ml per 100 g of tea leaves. After mixing evenly, the tea leaves are wrapped with wet gauze and fermented at 18-35° C. and a relative humidity of 60-95%. During the fermentation process, the tea leaves are turned over and water is added. The fermentation is completed when the tea leaves turn reddish brown.

[0082] (5) Drying: Dry at 90-120℃ for 30 minutes, cool and then oven dry at 60-80℃. The moisture content of the dried tea leaves is below 5%.

[0083] (6) Use hot water at about 97°C to brew black tea.

[0084] Example 9:

[0085] The black tea is prepared by the following process:

[0086] (1) Selecting tea raw materials: Select large-leaf tea trees from Luchun County, Honghe Prefecture, Yunnan Province, with one bud and two leaves as raw materials, wherein the moisture content of the raw materials is not less than 78%.

[0087] (2) Withering: Spread the fresh leaves in a withering tank at a height of 15-20 cm at 18-35°C. The relative humidity at the beginning of withering is 60-95%. Wither naturally for 4-11 hours until the color of the fresh leaves turns dark green, the leaves are curled and feel soft. At this time, the moisture content of the tea leaves is 60-65%.

[0088] (3) Rolling: The withered tea leaves are placed in a rolling machine for gentle rolling for 20-40 minutes, and then pressed and rolled for 10-15 minutes. The rolling machine is pressed so that the cover is in contact with the tea leaves. Add 5 ml of Trichoderma reesei suspension (OD600=1) and 5 ml of Bacillus subtilis suspension (OD600=1) per 100 g of tea leaves, and then gently roll for another 20-30 minutes on the rolling machine.

[0089] (4) Fermentation: After the tea leaves are rolled, 6 ml of yeast suspension (OD600 = 1) is added to the bacterial solution for every 100 g of tea leaves. After mixing evenly, the tea leaves are wrapped with wet gauze and fermented at 18-35°C and a relative humidity of 60-95%. During the fermentation process, the pile is turned and water is added. The fermentation is completed when the tea leaves turn reddish brown.

[0090] (5) Drying: Dry at 90-120℃ for 30 minutes, cool and then oven dry at 60-80℃. The moisture content of the dried tea leaves is below 5%.

[0091] (6) Use hot water at about 97°C to brew black tea.

[0092] Comparative Example 1:

[0093] A preparation process of black tea, the process comprising the following steps:

[0094] (1) Selecting tea raw materials: Select large-leaf tea trees from Luchun County, Honghe Prefecture, Yunnan Province, with one bud and two leaves as raw materials, wherein the moisture content of the raw materials is not less than 78%.

[0095] (2) Withering: Spread the fresh leaves in a withering tank at a height of 15-20 cm at 18-35°C. The relative humidity at the beginning of withering is 60-95%. Wither naturally until the leaves turn dark green, curl up, and feel soft. At this point, the moisture content of the tea leaves is 60-65%.

[0096] (3) Rolling: Put the withered tea leaves into the rolling machine for gentle rolling for 20-40 minutes. Then pressurize the rolling machine and roll for another 10-15 minutes. The rolling machine can be pressed until the cover is in contact with the tea leaves. Then roll the tea leaves gently for another 20-30 minutes.

[0097] (4) Fermentation: After the tea leaves are rolled, they are wrapped in gauze and fermented at 18-35°C and a relative humidity of 60-95%. During the fermentation process, the tea leaves are turned over and water is added. The fermentation is completed when the tea leaves turn reddish brown.

[0098] (5) Drying: Dry the tea leaves at a high temperature of 90-120°C for 30 minutes, cool them down and then dry them at 60-80°C. The moisture content of the dried tea leaves is less than 5%.

[0099] (6) Use hot water at about 97°C to brew black tea.

[0100] Comparative Example 2:

[0101] A preparation process of black tea, the process comprising the following steps:

[0102] (1) Selecting tea raw materials: Selecting small-leaf tea trees from Luchun County, Honghe Prefecture, Yunnan Province, with one bud and two leaves as raw materials, wherein the water content of the raw materials is not less than 78%.

[0103] (2) Withering: Spread the fresh leaves in a withering tank at a height of 15-20 cm at 18-35°C. The relative humidity at the beginning of withering is 60-95%. Wither naturally until the leaves turn dark green, curl up, and feel soft. At this point, the moisture content of the tea leaves is 60-65%.

[0104] (3) Rolling: Put the withered tea leaves into the rolling machine for gentle rolling for 20-40 minutes. Then pressurize the rolling machine and roll for another 10-15 minutes. The rolling machine can be pressed until the cover is in contact with the tea leaves. Then roll the tea leaves gently for another 20-30 minutes.

[0105] (4) Fermentation: After the tea leaves are rolled, they are wrapped in wet gauze and fermented at 18-35°C and a relative humidity of 60-95%. During the fermentation process, the tea leaves are turned over and water is added. The fermentation is completed when the tea leaves turn reddish brown.

[0106] (5) Drying: Dry the tea leaves at a high temperature of 90-120°C for 30 minutes, cool them down and then dry them at 60-80°C. The moisture content of the dried tea leaves is less than 5%.

[0107] (6) Use hot water at about 97°C to brew black tea.

[0108] The sensory evaluation of black tea was conducted according to the agricultural industry standard NY / T787-2004 "General Method for Sensory Evaluation of Tea". The sensory evaluation and physical and chemical analysis of the black tea prepared in Examples 1-9 and Comparative Examples 1-2 are shown in Table 1.

[0109] Table 1 Sensory evaluation and physicochemical analysis of black tea

[0110]

[0111] As can be seen from the above table, the black tea of ​​large-leaf tea and small-leaf tea in Lvchun County, Honghe Prefecture, Yunnan Province prepared by the present invention has good quality, and the tea soup is bright red, clear and transparent, with a strong aroma, mellow taste and a slightly sweet fragrance.

[0112] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A black tea preparation process based on microbial fermentation, characterized in that: The process includes the following steps: (1) Pick fresh tea leaves as raw materials and wither them naturally; (2) Mechanically or manually rolling the withered tea leaves prepared in step (1), and adding bacterial liquids of Bacillus subtilis and Trichoderma reesei for fermentation and hydrolysis; immediately adding yeast bacterial liquid for fermentation after the rolling is completed, and drying after the fermentation is completed to obtain black tea.

2. The process for preparing black tea based on microbial fermentation according to claim 1, characterized in that: The specific method of withering is: natural withering for 4-11 hours in an environment with a temperature of 18-35°C and a relative humidity of 60-95%, so that the water content of the tea leaves is reduced to 60-65%.

3. The process for preparing black tea based on microbial fermentation according to claim 1, characterized in that: The specific method of rolling is: use a rolling machine for mechanical rolling or direct manual rolling. Depending on the state of the fresh leaves, first roll lightly for 20-40 minutes, then pressurize and roll heavily for 10-15 minutes, add Bacillus subtilis and Trichoderma reesei solution, and then roll gently for 20-30 minutes.

4. The process for preparing black tea based on microbial fermentation according to claim 1, characterized in that: The specific method of fermentation is: add yeast liquid, mix evenly, wrap the tea leaves with wet gauze, ferment in an environment of 18-35°C and relative humidity of 60-95%, turn the pile and add water during the fermentation process, and end the fermentation when the tea leaves turn reddish brown.

5. The process for preparing black tea based on microbial fermentation according to claim 1, characterized in that: Add bacterial liquid at a ratio of 1-10 ml of Bacillus subtilis liquid (OD600=1) per 100 grams of tea leaves; add bacterial liquid at a ratio of 1-10 ml of Trichoderma reesei suspension (OD600=1) per 100 grams of tea leaves; add bacterial liquid at a ratio of 1-12 ml of yeast liquid (OD600=1) per 100 grams of tea leaves.

6. The process for preparing black tea based on microbial fermentation according to claim 1, characterized in that: The height of the withered leaves in step (1) is 10-15 cm.

7. The process for preparing black tea based on microbial fermentation according to claim 1, characterized in that: In the step (2), Bacillus subtilis and Trichoderma reesei are added during the rolling process to promote the hydrolysis and saccharification of cellulose and the breakage of cell walls during the rolling process.

8. The process for preparing black tea based on microbial fermentation according to claim 1, characterized in that: The temperature of the kneading in the step (2) is 20-28° C., and the relative humidity is 70-80%.

9. The process for preparing black tea based on microbial fermentation according to claim 1, characterized in that: In the step (2), Bacillus subtilis, Trichoderma reesei and yeast are added respectively to carry out natural fermentation or fermentation under temperature and humidity control.

10. The process for preparing black tea based on microbial fermentation according to claim 1, characterized in that: After the fermentation in step (2) is completed, the tea is dried at 90-120° C. for 30 minutes, cooled, and then dried at 60-80° C. until the moisture content is 5%, thereby obtaining black tea.

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