Directional debitterizing yellow tea preparation process

Abstract

The invention discloses a preparation technology of directional debitterizing yellow tea, and belongs to the technical field of tea processing. Fresh tea leaves are used as raw materials, the yellow tea is prepared through the processes of pretreatment, fermentation, fixation, rolling, heaping for yellowing and drying, during fermentation, a compound bacteria solution and the spread and aired fresh leaves are mixed and fermented, strains in the compound bacteria solution comprise lactic acid bacteria, saccharomycetes and bacillus, and through the synergistic effect of the lactic acid bacteria, the saccharomycetes and the bacillus, the yellow tea is prepared. Balancing of directional degradation of bitter and astringent substances and generation of flavor substances is achieved, high-quality yellow tea is prepared through efficient debitterizing, the stage heaping yellowing technology is adopted, primary heaping and secondary heaping are adopted for two-stage heaping yellowing, the quality of the yellow tea is enhanced, and poor taste caused by excessive heaping yellowing is avoided. According to the finished tea prepared by the preparation process, the content of tea polyphenol is reduced to 18%-20% through detection, the content of amino acid reaches 4.5%-5.0%, bitter taste and astringent taste are relieved, sweet taste is added, and the taste is mellow.

Description

Technical Field

[0001] The invention belongs to the technical field of tea processing, and particularly relates to a process for preparing directed debittered yellow tea. Background Art

[0002] Yellow tea is a unique tea type in my country, evolved from green tea. The main process for yellow tea processing involves fresh leaf preparation, spreading, withering, yellowing, and drying. Yellowing is the key step. During yellowing, the withering leaves are stacked while still hot, causing thermochemical changes in the moist heat, ultimately turning the leaves yellow. Essentially, high temperature and high water content degrade the chlorophyll in the tea leaves, leading to non-enzymatic oxidation of polyphenols, producing yellow substances. This results in the yellow or yellowish-brown color of the dry tea and the leaf base, as well as a sweet and mellow flavor.

[0003] However, the duration of the yellowing process is difficult to control. If the yellowing is not done enough, a bitter taste will remain in the tea leaves, while if it is done too much, the color will become darker and the aroma will be weakened, which will affect the sensory quality of yellow tea and reduce its market competitiveness. As the yellowing time increases, the proportion of tea polyphenols and amino acids in the tea leaves gradually decreases, and the bitterness of the tea leaves is reduced.

[0004] Wild tea generally grows in wild mountains or high-altitude areas with poor soil and cold climate. These environmental factors make the growth cycle of tea trees longer and the chemical components in the leaves relatively rich, which leads to a higher degree of bitterness in the tea. In order to reduce the bitterness of wild tea, the traditional yellow tea processing technology prolongs the yellowing process when processing wild tea, making it difficult to effectively remove the bitterness of wild tea, reducing production efficiency and affecting product quality. Summary of the Invention

[0005] The invention provides a directional debittering yellow tea preparation process, which can solve the problems of poor debittering effect and low efficiency in wild tea processing in the prior art.

[0006] The purpose of the present invention can be achieved through the following technical solutions: A process for preparing directed debittered yellow tea comprises the following steps: S1, pretreatment: screening fresh leaves for airing; S2, fermentation: preparing a composite bacterial solution, mixing the fresh leaves with the composite bacterial solution after airing, and then fermenting in a fermentation tank; S3, fixing: fixing the fermented leaves in a steam fixing machine; S4, rolling: the withered leaves are rolled using a cold rolling process to form rolled leaves; S5, yellowing: Wrap the rolled leaves in wet cloth and yellow at 25-28℃ for the first time, then dry them until the moisture content is 30%-35%, and then yellow again at 20-25℃ and humidity 60%-70%; S6. Drying: Dry the yellow leaves at 80-90℃ until the moisture content is 15%-20%, and then dry them at 60-70℃ until the moisture content is ≤6%; The bacterial species in the composite bacterial liquid include lactic acid bacteria, yeast and bacillus.

[0007] During the traditional yellow tea brewing process, chlorophyll degradation causes the tea leaves to gradually transform from green to yellow. Simultaneously, polyphenolic compounds undergo non-enzymatic oxidation reactions, producing colored substances such as theaflavins and thearubigins. These not only impart a golden color to the yellow tea but also enhance its aroma and richness. The amino acid and soluble sugar content in the tea increase. The increase in amino acids contributes to the tea's freshness, while the increase in soluble sugars enhances the sweetness and body of the tea. Microorganisms in the tea leaves (such as Aspergillus niger and yeasts) thrive in hot and humid conditions. The enzymes they produce (such as polyphenol oxidase and peroxidase) further promote chemical reactions within the tea, accelerating the yellowing process and the formation of flavor compounds.

[0008] However, the yellowing process of traditional yellow tea mainly relies on the tea leaves’ own endogenous enzymes (polyphenol oxidase, etc.) and humid and hot conditions. Although microorganisms in the environment may be involved, it is usually non-directional and uncontrollable.

[0009] The present invention prepares a composite bacterial liquid composed of lactic acid bacteria, yeast and bacillus to carry out controllable fermentation of fresh leaves before withering. Before withering, the cell structure of the fresh leaves is complete, the endogenous enzyme activity is high, and the nutrients are rich, which provides a more suitable growth environment and substrate for exogenous microorganisms. Withering is carried out after fermentation, and the high temperature of withering can be used for sterilization to terminate the activity of the microorganisms brought by the composite bacterial liquid and control the fermentation effect.

[0010] Using composite bacterial liquid for fermentation, on the one hand, the microorganisms are more active, can reproduce and metabolize quickly, accelerate the transformation of substances in the tea, efficiently remove bitterness, and shorten the subsequent yellowing cycle. Traditional yellowing usually takes several days or even longer to achieve a similar effect; on the other hand, the transformed substances under the joint action of three different strains can better enhance the aroma layering of the finished tea.

[0011] The above drying process adopts two-step drying. The initial drying fixes the shape, and the secondary drying ensures that the moisture content is reduced, making the tea more resistant to storage, while stimulating the compound aroma of fungus and flowers.

[0012] Furthermore, the fresh leaves in S1 are fresh leaves with one bud and one leaf or one bud and two leaves from the wild hairy-leaf tea tree in Nankun Mountain, and pests and damaged leaves are removed.

[0013] Nankunshan Maocha is primarily grown wild, primarily from tree- and arbor-type tea plants. It boasts higher levels of tea polyphenols than typical teas, with minimal or no caffeine. It is the only naturally grown caffeine-free tea variety in the world. The purine alkaloids in this Maocha are primarily theobromine, which does not affect sleep quality but may actually promote it.

[0014] Furthermore, the moisture content of the fresh leaves in S1 is 75%-80%.

[0015] Furthermore, the duration of the airing is 8-10 hours, the thickness of the airing is 3-5 cm, the airing is stirred 2-3 times during the airing, and the moisture content of the fresh leaves after airing is 65%-70%. Airing in a ventilated environment promotes the improvement of the softness of the fresh leaves.

[0016] Furthermore, the composite bacterial solution is prepared as follows: Lactic acid bacteria, yeast and Bacillus agents were inoculated into sterile culture medium to form three kinds of bacterial liquids, and the number of viable bacteria in the bacterial liquids was ≥1×10 8 CFU / mL, according to the number of viable bacteria (2-4): (1-3): (1-3) three bacterial solutions were mixed to obtain a composite bacterial solution; The number of viable bacteria of the lactic acid bacteria agent is ≥1×10 11 CFU / g, the number of viable bacteria of yeast inoculant ≥1×10 10 CFU / g, the number of viable bacteria of Bacillus inoculum ≥1×10 10 CFU / g.

[0017] Lactic acid bacteria metabolize to produce organic acids, which lower the pH of the fermentation system. A low pH environment is more conducive to increasing the activity of endogenous enzymes in tea leaves and enzymes secreted by exogenous microorganisms, converting the ester bonds of ester-type catechins into simple catechins, thereby reducing the bitterness of the tea and enhancing its freshness. Yeast fermentation produces aromatic substances such as alcohols and esters, which are important components of the characteristic aroma of yellow tea. Bacillus can secrete various hydrolases that hydrolyze proteins in tea leaves to produce amino acids, significantly enhancing the flavor and aroma of yellow tea. The small molecules produced by hydrolysis serve as nutrients for lactic acid bacteria and yeast, promoting their growth. The three bacteria work synergistically to rapidly degrade bitter substances and improve the quality of yellow tea. The bacterial strains metabolize to produce polyphenol oxidases and hydrolases, which degrade tea polyphenols while generating amino acids, achieving debittering and enhancing freshness.

[0018] Furthermore, the mixing mass ratio of the fresh leaves after spreading and airing to the composite bacterial liquid is 100:0.5-1.0.

[0019] Furthermore, the fermentation conditions are as follows: The temperature is 28-32℃, the humidity is 75%-80%, and fermentation is carried out in an anaerobic environment for 14-16 hours.

[0020] Furthermore, the temperature for withering is 120-130° C., and the withering time is 3-5 minutes, which quickly terminates the enzyme activity and fixes the bacterial debittering effect.

[0021] Furthermore, the cold kneading process is as follows: Spread the withered leaves out to cool to room temperature, then place them in a rolling machine for rolling. Set the rolling machine speed to 40-50 r / min and the rolling time to 15-20 minutes. The rolled leaves are formed into a tight strip to prevent excessive cell breakage and the precipitation of bitter substances.

[0022] Furthermore, the duration of the initial stuffiness is 10-14 hours, and the duration of the secondary stuffiness is 22-26 hours.

[0023] Beneficial effects of the present invention: (1) The present invention is the first to use wild hairy-leaf tea trees from Nankun Mountain for the preparation of debittered yellow tea by bacterial culture. The fermentation parameters are optimized in combination with the characteristics of the leaves, and a composite bacterial agent is used for synergistic debittering. Through the synergistic action of lactic acid bacteria, yeast, and Bacillus, a balance is achieved between the directional degradation of bitter substances and the generation of flavor substances. High-quality yellow tea is prepared by efficient debittering, forming the unique "three yellow" quality of yellow tea (yellow dry tea, yellow soup color, and yellow leaf bottom).

[0024] (2) The present invention adopts a segmented yellowing process, which includes two stages: initial yellowing and secondary yellowing, to enhance the quality of yellow tea while avoiding the deterioration of taste caused by excessive yellowing.

[0025] (3) The finished tea obtained by the preparation process of the present invention has a uniform appearance, a yellow and rosy color, a bright orange-yellow soup color, an aroma that combines the wild charm of wild tea with the fermented aroma after fungation, and a mellow taste without bitterness.

[0026] (4) The tea polyphenol content of the finished tea obtained by the preparation process of the present invention was reduced to 18%-20%, and the amino acid content was 4.5%-5.0%. The bitterness and astringency were reduced, and the sweetness was increased, which met the standards of high-quality yellow tea. DETAILED DESCRIPTION

[0027] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0028] Example 1 A process for preparing directed debittered yellow tea comprises the following steps: S1. Pretreatment: Pick fresh leaves with one bud and one leaf or one bud and two leaves from wild hairy-leaf tea trees in Nankun Mountain, Longmen County, Guangdong Province, remove diseased and insect pests and damaged leaves, select fresh leaves with a moisture content of 75%-80%, place the fresh leaves in a ventilated environment and spread them out to dry for 10 hours with a thickness of 3-5 cm, stir them 3 times during the period to reduce the moisture content to 65%-70% and improve the softness of the fresh leaves.

[0029] S2, fermentation: prepare compound bacterial solution, buy lactic acid bacteria (1×10 11 CFU / g), yeast (1×10 10 CFU / g) and Bacillus (1×10 10 CFU / g), lactic acid bacteria were inoculated into sterile MRS medium with an inoculation volume of 1%, and cultured under anaerobic conditions at 37°C for 12 h. The number of viable bacteria in the culture solution was ≥1×10 10 CFU / mL, inoculate the yeast into sterile YPD liquid medium with an inoculation volume of 1%, culture at 30℃ under sufficient oxygen for 12h, and the number of viable bacteria in the culture liquid should be ≥1×10 10 CFU / mL, inoculate Bacillus into sterile nutrient broth medium with an inoculation volume of 1%, culture at 35℃ under sufficient oxygen for 12h, and the number of viable bacteria in the culture solution should be ≥1×10 10 CFU / mL, a composite bacterial solution was prepared by mixing the three bacterial solutions of lactic acid bacteria, yeast, and Bacillus at a ratio of 3:2:1. After airing, the fresh leaves were mixed with the composite bacterial solution at a mass ratio of 100:0.8. The mixture was then fermented in a fermenter at a temperature of 28-32°C and a humidity of 75%-80% under anaerobic conditions for 15 hours.

[0030] S3. Fixing: Put the fermented leaves into the steam fixing machine after fermentation, set the fixing temperature to 125℃, and fix for 4 minutes.

[0031] S4. Rolling: Spread the fixed leaves out to cool to room temperature, then put them into a rolling machine for rolling. Set the speed of the rolling machine to 40 r / min and the rolling time to 20 min to form tightly bound strips of rolled leaves.

[0032] S5. Yellowing: Wrap the rolled leaves with a wet cloth, and yellow them for 12 hours at room temperature of 25℃. Take them out and dry them until the moisture content is 30%-35%, and then yellow them again at 20℃ and humidity of 65% for 24 hours.

[0033] S6. Drying: Dry the yellow leaves at 85℃ until the moisture content is 15%-20%, and then dry them at 65℃ until the moisture content is ≤6%.

[0034] Example 2 The only difference from Example 1 is that the mass ratio of fresh leaves to composite bacterial solution after airing in S2 is adjusted from 100:0.8 to 100:0.5.

[0035] Example 3 The only difference from Example 1 is that the mass ratio of fresh leaves to composite bacterial solution after airing in S2 is adjusted from 100:0.8 to 100:1.0.

[0036] Example 4 The only difference from Example 1 is that the ratio of the number of live bacteria of lactic acid bacteria, yeast and Bacillus in the composite bacterial liquid in S2 is adjusted to 2:3:1.

[0037] Example 5 The only difference from Example 1 is that the ratio of the number of live bacteria of lactic acid bacteria, yeast and Bacillus in the composite bacterial liquid in S2 is adjusted to 4:1:1.

[0038] Example 6 The only difference from Example 1 is that the ratio of the number of live bacteria of lactic acid bacteria, yeast and Bacillus in the composite bacterial liquid in S2 is adjusted to 2:2:2.

[0039] Example 7 The only difference from Example 1 is that the ratio of the number of live bacteria of lactic acid bacteria, yeast and Bacillus in the composite bacterial liquid in S2 is adjusted to 1:2:3.

[0040] Comparative Example 1 The only difference from Example 1 is that fermentation is not performed in the preparation process of this comparative example.

[0041] A process for preparing directed debittered yellow tea comprises the following steps: S1. Pretreatment: Pick fresh leaves with one bud and one leaf or one bud and two leaves from wild hairy-leaf tea trees in Nankun Mountain, Longmen County, Guangdong Province, remove diseased and insect pests and damaged leaves, select fresh leaves with a moisture content of 75%-80%, place the fresh leaves in a ventilated environment and spread them out to dry for 10 hours with a thickness of 3-5 cm, stir them 3 times during the period to reduce the moisture content to 65%-70% and improve the softness of the fresh leaves.

[0042] S2. Fixing: put the fresh leaves after drying into the steam fixing machine, set the fixing temperature to 125℃, and fix for 4 minutes.

[0043] S3. Rolling: Spread the fixed leaves out to cool to room temperature, then put them into a rolling machine for rolling. Set the speed of the rolling machine to 40 r / min and the rolling time to 20 min to form tightly bound strips of rolled leaves.

[0044] S4. Yellowing: Wrap the rolled leaves with a wet cloth, and yellow them for 12 hours at room temperature of 25℃. Take them out and dry them until the moisture content is 30%-35%, and then yellow them again at 20℃ and humidity of 65% for 24 hours.

[0045] S5. Drying: Dry the yellow leaves at 85℃ until the moisture content is 15%-20%, and then dry them at 65℃ until the moisture content is ≤6%.

[0046] Comparative Example 2 The only difference from Example 1 is that the yellowing in this comparative example is not performed in stages.

[0047] A process for preparing directed debittered yellow tea comprises the following steps: S1. Pretreatment: Pick fresh leaves with one bud and one leaf or one bud and two leaves from wild hairy-leaf tea trees in Nankun Mountain, Longmen County, Guangdong Province, remove diseased and insect pests and damaged leaves, select fresh leaves with a moisture content of 75%-80%, place the fresh leaves in a ventilated environment and spread them out to dry for 10 hours with a thickness of 3-5 cm, stir them 3 times during the period to reduce the moisture content to 65%-70% and improve the softness of the fresh leaves.

[0048] S2, fermentation: prepare compound bacterial solution, buy lactic acid bacteria (1×10 11 CFU / g), yeast (1×10 10 CFU / g) and Bacillus (1×10 10 CFU / g), lactic acid bacteria were inoculated into sterile MRS medium with an inoculation volume of 1%, and cultured under anaerobic conditions at 37°C for 12 h. The number of viable bacteria in the culture solution was ≥1×10 10 CFU / mL, inoculate the yeast into sterile YPD liquid medium with an inoculation volume of 1%, culture at 30℃ under sufficient oxygen for 12h, and the number of viable bacteria in the culture liquid should be ≥1×10 10 CFU / mL, inoculate Bacillus into sterile nutrient broth medium with an inoculation volume of 1%, culture at 35℃ under sufficient oxygen for 12h, and the number of viable bacteria in the culture solution should be ≥1×10 10 CFU / mL, a composite bacterial solution was prepared by mixing the three bacterial solutions of lactic acid bacteria, yeast, and Bacillus at a ratio of 3:2:1. After airing, the fresh leaves were mixed with the composite bacterial solution at a mass ratio of 100:0.8. The mixture was then fermented in a fermenter at a temperature of 28-32°C and a humidity of 75%-80% under anaerobic conditions for 15 hours.

[0049] S3. Fixing: Put the fermented leaves into the steam fixing machine after fermentation, set the fixing temperature to 125℃, and fix for 4 minutes.

[0050] S4. Rolling: Spread the fixed leaves out to cool to room temperature, then put them into a rolling machine for rolling. Set the speed of the rolling machine to 40 r / min and the rolling time to 20 min to form tightly bound strips of rolled leaves.

[0051] S5. Yellowing: Roll the leaves and wrap them in a wet cloth, and yellow them at room temperature of 25℃ for 36 hours.

[0052] S6. Drying: Dry the yellow leaves at 85℃ until the moisture content is 15%-20%, and then dry them at 65℃ until the moisture content is ≤6%.

[0053] Comparative Example 3 The only difference from Example 1 is that the strain used for fermentation in this comparative example is only yeast.

[0054] A process for preparing directed debittered yellow tea comprises the following steps: S1. Pretreatment: Pick fresh leaves with one bud and one leaf or one bud and two leaves from wild hairy-leaf tea trees in Nankun Mountain, Longmen County, Guangdong Province, remove diseased and insect pests and damaged leaves, select fresh leaves with a moisture content of 75%-80%, place the fresh leaves in a ventilated environment and spread them out to dry for 10 hours with a thickness of 3-5 cm, stir them 3 times during the period to reduce the moisture content to 65%-70% and improve the softness of the fresh leaves.

[0055] S2, fermentation: prepare compound bacterial solution, purchase yeast (1×10 10 CFU / g), the yeast was inoculated into sterile YPD liquid culture medium with an inoculation volume of 1%, and cultured at 30℃ under sufficient oxygen for 12h. The number of viable bacteria in the culture liquid was ≥1×10 10 After airing, the fresh leaves were mixed with the composite bacterial solution at a mass ratio of 100:0.8 and fermented in a fermenter at a temperature of 28-32°C and a humidity of 75%-80% under anaerobic conditions for 15 hours.

[0056] S3. Fixing: Put the fermented leaves into the steam fixing machine after fermentation, set the fixing temperature to 125℃, and fix for 4 minutes.

[0057] S4. Rolling: Spread the fixed leaves out to cool to room temperature, then put them into a rolling machine for rolling. Set the speed of the rolling machine to 40 r / min and the rolling time to 20 min to form tightly bound strips of rolled leaves.

[0058] S5. Yellowing: Wrap the rolled leaves with a wet cloth, and yellow them for 12 hours at room temperature of 25℃. Take them out and dry them until the moisture content is 30%-35%, and then yellow them again at 20℃ and humidity of 65% for 24 hours.

[0059] S6. Drying: Dry the yellow leaves at 85℃ until the moisture content is 15%-20%, and then dry them at 65℃ until the moisture content is ≤6%.

[0060] The quality of the yellow tea prepared in Examples 1 to 7 and Comparative Examples 1 to 3 was evaluated with reference to GB / T 23776-2018 Tea Sensory Evaluation Method, and the tea polyphenol content in the yellow tea was tested. The results are shown in Table 1: Table 1 As can be seen from Table 1, the preparation process of the embodiment of the present invention is optimized on the traditional yellow tea preparation process. Yellow tea is prepared through the steps of pretreatment, fermentation, withering, rolling, yellowing and drying, which achieves efficient and targeted degradation of bitter substances, enhances the flavor of yellow tea, and has a lower content of tea polyphenols and a higher content of amino acids, making the taste more fresh, mellow and refreshing.

[0061] Compared with Example 1, in Comparative Example 1, the same yellowing time was insufficient to meet the yellowing requirement of yellow tea without fermentation, the material conversion was not sufficient, and the astringency was heavier. In Comparative Example 2, the continuous yellowing without segmented yellowing resulted in a slightly darker color and a lack of brightness in the tea soup. In Comparative Example 3, the fermentation conversion reaction was simple when a single yeast was used for fermentation, and some substances were difficult to rely on yeast for conversion, resulting in a higher content of retained tea polyphenols than in Example 1, a lower efficiency in converting protein into amino acids, and a slightly astringent taste.

[0062] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0063] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A process for preparing directional debittered yellow tea, characterized in that: The following steps are involved: S1, pretreatment: screening fresh leaves for airing; S2, fermentation: preparing a composite bacterial solution, mixing the fresh leaves with the composite bacterial solution after airing, and then fermenting in a fermentation tank; S3, fixing: fixing the fermented leaves in a steam fixing machine; S4, rolling: the withered leaves are rolled using a cold rolling process to form rolled leaves; S5, yellowing: Wrap the rolled leaves in wet cloth and yellow at 25-28℃ for the first time, then dry them until the moisture content is 30%-35%, and then yellow again at 20-25℃ and humidity 60%-70%; S6. Drying: Dry the yellow leaves at 80-90℃ until the moisture content is 15%-20%, and then dry them at 60-70℃ until the moisture content is ≤6%; The bacterial species in the composite bacterial liquid include lactic acid bacteria, yeast and bacillus.

2. The process for preparing directional debittered yellow tea according to claim 1, wherein: The fresh leaves in S1 are fresh leaves with one bud and one leaf or one bud and two leaves from wild hairy-leaf tea trees in Nankun Mountain.

3. The process for preparing directional debittered yellow tea according to claim 1, wherein: The moisture content of the fresh leaves in S1 is 75%-80%.

4. The process for preparing directional debittered yellow tea according to claim 1, characterized in that: The duration of the airing is 8-10 hours, the thickness of the airing is 3-5 cm, the leaves are turned over 2-3 times during the airing, and the moisture content of the fresh leaves after airing is 65%-70%.

5. The process for preparing directed debittered yellow tea according to claim 1, characterized in that: The composite bacterial solution is prepared as follows: Lactic acid bacteria, yeast and Bacillus agents were inoculated into sterile culture medium to form three kinds of bacterial liquids, and the number of viable bacteria in the bacterial liquids was ≥1×10 8 CFU / mL, according to the number of viable bacteria (2-4): (1-3): (1-3) three bacterial solutions were mixed to obtain a composite bacterial solution; The number of viable bacteria of the lactic acid bacteria agent is ≥1×10 11 CFU / g, the number of viable bacteria of yeast inoculant ≥1×10 10 CFU / g, the number of viable bacteria of Bacillus inoculum ≥1×10 10 CFU / g.

6. The process for preparing directed debittered yellow tea according to claim 1, characterized in that: The mixing mass ratio of the fresh leaves after spreading and airing to the composite bacterial liquid is 100:0.5-1.

0.

7. The process for preparing directed debittered yellow tea according to claim 1, characterized in that: The fermentation conditions are as follows: The temperature is 28-32℃, the humidity is 75%-80%, and fermentation is carried out in an anaerobic environment for 14-16 hours.

8. The process for preparing directed debittered yellow tea according to claim 1, characterized in that: The temperature for the fixing is 120-130° C., and the fixing time is 3-5 minutes.

9. The process for preparing directed debittered yellow tea according to claim 1, characterized in that: The cold kneading process is as follows: The withered leaves are spread out to cool to room temperature, and then put into a rolling machine for rolling. The speed of the rolling machine is set to 40-50r / min, and the rolling time is 15-20min to form tightly bound strips of rolled leaves to avoid excessive cell breakage and the precipitation of bitter substances.

10. The process for preparing directed debittered yellow tea according to claim 1, characterized in that: The duration of the initial stuffiness is 10-14 hours, and the duration of the secondary stuffiness is 22-26 hours.

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