CN112273483B

CN112273483B - Method for preparing black tea by aging green tea

Info

Publication number: CN112273483B
Application number: CN202011358693.3A
Authority: CN
Inventors: 唐华; 赵和涛; 殷虎
Original assignee: Qimen Youchaji Tea Professional Cooperative
Current assignee: Qimen Youchaji Tea Professional Cooperative
Priority date: 2020-11-27
Filing date: 2020-11-27
Publication date: 2023-05-23
Anticipated expiration: 2040-11-27
Also published as: CN112273483A

Abstract

The invention discloses a method for preparing black tea by aging green tea, which comprises the following steps: the method comprises the steps of S1 heating for ageing, S2 water softening, S3 enzymatic piling, S4 microwave dehydration, S5 blending and proportioning, S6 mixing and primary kneading, S7 enzymatic re-kneading, S8 deblocking and screening, S9 sugar fermentation, S10 enzymatic fermentation, S11 drying, S12 color selection and stem sorting, S13 winnowing and impurity removal, S14 screening, S15 microwave aroma extraction and S16 lotus leaf scenting. The invention uses the basic manufacturing principles of black tea withering, rolling, fermenting, drying and the like, and applies new technologies of enzymatic softening and piling, enzyme-sugar mixed fermentation, microwave sterilization and aroma extraction, lotus leaf scenting and the like to convert aged green tea into black tea, thereby not only enhancing the efficient utilization of aged tea resources, but also optimizing the tea quality and drinking value of the aged green tea, and having excellent economic and social benefits.

Description

Method for preparing black tea by aging green tea

Technical Field

The invention belongs to the technical field of tea processing, and particularly relates to a method for preparing black tea by using aged green tea.

Background

The green tea is a kind of tea which is least easy to preserve, and if the green tea is improperly stored or excessively stored for too long, various components such as fat, cellulose, amino acid, tea polyphenol, pigment and the like contained in the tea are easily changed under the influence of environmental conditions, and the change of the components can lead to obvious reduction of the sensory quality such as tea color, aroma, soup color, taste and the like, so that the aged green tea is changed.

Aged green tea often contains a strong stale flavor, not only color, aroma, taste, shape, but also has adverse effects on the body after long-term drinking, and thus is difficult to attract consumers. It is known that about 10-20 ten thousand tons of aged green tea stock are sold in China every year, and the tea resources are wasted greatly. Therefore, how to solve the problem that the aged green tea resource is changed into valuable is a relatively concerned problem in the current tea industry in China.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a method for preparing black tea by using aged green tea, which uses the basic manufacturing principles of black tea withering, rolling, fermenting, drying and the like, and applies new technologies of enzymatic softening and piling, enzyme-sugar mixed fermentation, electrothermal drying, microwave sterilization and aroma extraction and the like to convert the aged green tea into black tea, thereby not only enhancing the efficient utilization of the aged tea resources, but also optimizing the tea quality and drinking value of the aged green tea, and having excellent economic and social benefits.

The aim of the invention is realized by the following technical scheme:

a method for preparing black tea from aged green tea comprising the steps of:

s1, heating to remove ageing: heating aged green tea with electrothermal dryer at 120-130deg.C to remove stale;

s2, softening by adding water: adding aged green tea with removed smell into 40-50deg.C warm water, soaking for 1-2 hr, and softening to obtain wet tea after the aged green tea absorbs water;

s3, enzymatic pile fermentation: adding cellulase into the wet tea, and enzymatically piling for 6-8 hours; cellulose can decompose cellulose, and cellulose is a main component of cell walls, so that the cellulose can destroy the cell walls of tea cells, and the tea cells are convenient to knead into strips in the subsequent process; in addition, substances such as starch and the like contained in the tea can overflow fully after the cells of the tea are destroyed, so that the concentration of the substrate for enzymolysis by the subsequent saccharifying enzyme can be increased, and the subsequent enzymolysis efficiency is improved; in addition, the enzymolysis product in the cellulose enzymolysis process is glucose, so that the total sugar content of the tea can be increased, and the taste of the black tea is increased and the taste of the tea is more sweet and mellow along with the outflow of tea soup in the brewing process.

S4, microwave dehydration: placing the aged green tea subjected to enzymatic pile fermentation into microwave dehydration equipment for microwave dehydration treatment to obtain pretreated aged green tea; preferably, the microwave dehydration equipment is a microwave tempering dehydrator. The microwave is adopted for dehydration, so that the harmful microorganisms and germs in the aged tea can be eliminated by utilizing the action of the microwave while the moisture is removed;

s5, blending: withering fresh tea leaves to obtain withered fresh leaves, and mixing the withered fresh leaves with the pretreated aged green tea prepared in the step S4 to obtain a mixture of 1: mixing the components in the mass ratio of (1-1.2) to obtain the mixed tea. The withering treatment comprises the following steps: naturally withering fresh tea leaves on a bamboo mat for 1-2 hours in a room temperature environment, and then withering the fresh tea leaves for 0.5-1 hour in sunlight to promote the enzymatic reaction of polyphenol oxidase in the fresh tea leaves to be enhanced; finally, the fresh tea leaves subjected to sunlight withering are put into a withering tank, and hot air withering is carried out for 1-2 hours by using hot air at the temperature of 32-34 ℃.

S6, mixing and primary kneading: the mixed tea leaves are kneaded for the first time, the mixed tea leaves are gentle for 10 minutes, and tea cells are promoted to destroy tea juice and overflow, so that the mixed tea leaves are primarily formed into strips;

s7, enzyme is added for re-kneading: adding saccharifying enzyme with mass of 0.3-0.4% into the primarily-formed mixed tea, and twisting again to make the mixed tea basically formed into strips. The step of re-twisting is as follows: firstly, lightly kneading for 8-12min, then, pressurizing and re-kneading for 25-35min, and finally, non-pressurizing and loosening and kneading for 4-6min. After the re-rolling is completed, the breakage rate of the tea cells reaches 80-90%. Mixing and twisting the withered fresh leaves and the aged green tea, so that polyphenol oxidase in the fresh leaves permeates into the aged green tea, and activating enzymatic reaction; meanwhile, the aged green tea is considered to be different in components and properties from fresh leaves, and the fermentation difficulty is high, so that saccharifying enzyme is additionally added in the step, and the saccharifying enzyme and the aged green tea are fully mixed by rolling operation, so that the saccharification degree of the aged green tea is promoted, the bitter and astringent taste of the aged green tea is reduced, and the conversion of the aged green tea into the quality of black tea is promoted.

S8, deblocking and screening: screening the mixed tea leaves which are basically formed into strips, so that the mixed tea leaves are fully dispersed and do not agglomerate;

s9, sugar adding fermentation: adding brown sugar 1-1.5% of the mixed tea after deblocking and sieving, stirring uniformly, naturally fermenting at 32-33deg.C for 1-1.5 hr, keeping the humidity of the fermentation chamber at 85-90%, and timely ventilating and supplying oxygen;

s10, enzymatic fermentation: adding saccharifying enzyme with the mass of 0.2-0.3% into the mixed tea after natural fermentation, stirring uniformly, and then carrying out enzymatic fermentation to obtain black tea; the temperature of the enzymatic fermentation is 33-34 ℃, the time is 2-2.5 hours, and the ambient humidity is 85-90%. Fermenting the aged tea fully by enzymatic fermentation to turn red;

s11, drying: the method comprises the following steps of: firstly, hot air drying is carried out on black tea by a hot air dryer at the temperature of 125-130 ℃ to ensure that the water content of the black tea is 45-50%; then blowing cold air to the black tea by using a cooling and conditioning machine to make the surface water of the black tea emit and the internal water overflows; finally, using a hot air dryer to perform hot air foot drying at the temperature of less than or equal to 120 ℃ so that the water content of the black tea reaches 7-8%.

S12, selecting stems: selecting stems of the dried black tea by using a tea She Zhineng color sorter, and removing sundries such as tea stems, tea fruits and the like;

s13, winnowing and impurity removal: performing air separation on black tea after color selection and stem sorting to remove impurities, and further blowing out tea slices, tea leaves, tea ash and impurities to obtain clean and even tea leaves;

s14, classifying and grading: classifying by adopting a plane round screen machine by using two screens with 12 holes and 6 holes, wherein tea leaves below the screen surface with 12 holes are black powder tea, tea leaves above 12 holes and below 6 holes are broken black tea, and tea leaves on the screen surface with 6 holes are raw black tea;

s15, microwave aroma extraction: sterilizing and extracting fragrance of the black powder tea, the broken black tea and the black crude tea by using a microwave fragrance extracting machine; the high-temperature aroma extraction and the microwave sterilization are carried out, so that the quality safety of the product is ensured, and the water content of the black tea after aroma extraction is between 5.5 and 6 percent;

s16 lotus leaf scenting: respectively placing the minced black tea, broken black tea and crude black tea subjected to microwave aroma extraction into a sealed container, and paving and stacking the minced black tea, the broken black tea and the crude black tea in a mode of wrapping a layer of tea leaves and a layer of dried lotus leaves, and then scenting; the scenting time is three days, and the peculiar faint scent of the lotus leaves is soaked into the black tea through the scenting, so that the lotus leaves form unique lotus-fragrance tea; removing the lotus leaf bag after the scenting is finished, and then sealing and packaging various black tea to obtain the final product.

Compared with the prior art, the invention has the beneficial effects that:

(1) Firstly, adding water into aged green tea with stale removed to soften the aged green tea into wet tea, and then, carrying out enzymatic pile fermentation on the wet tea by using cellulase, wherein the cellulase can decompose cellulose in the enzymatic pile fermentation process so as to destroy cell walls of tea cells and facilitate subsequent kneading into strips; on the other hand, after the tea cells are destroyed, substances such as starch in the tea can overflow fully, so that the concentration of the substrate for enzymolysis of the subsequent saccharifying enzyme can be increased, and the subsequent enzymolysis efficiency is improved; in addition, the enzymolysis product of the cellulose is glucose, so that the total sugar content of the tea can be increased, and the taste of the black tea is increased along with the outflow of tea soup in the brewing process, so that the taste of the tea is more sweet and mellow, and the quality of the product is improved.

(2) According to the invention, the withered fresh leaves and the aged green tea are mixed and rolled, so that polyphenol oxidase in the fresh leaves permeates into the aged green tea, the enzymatic reaction is activated, and the green tea is promoted to be converted into the black tea; in addition, saccharifying enzyme is added in the enzyme adding and kneading step, and kneading operation is utilized to fully mix the saccharifying enzyme with the aged green tea, so that the saccharification degree of the aged green tea is promoted, the bitter and astringent taste of the aged green tea is reduced, and the conversion of the aged green tea into the quality of black tea is promoted.

(3) The sugar fermentation and enzymatic fermentation binary fermentation procedures are adopted, so that the fermentation degree of the aged tea can be improved, the formation of red leaves special for black tea can be accelerated, and the sweet quality can be formed. In addition, the brown sugar has mild nature, and contains various microelements, wherein some microelements can stimulate the hematopoietic function of the organism, and has the effects of nourishing blood and supplementing blood; black tea is sweet and warm, can nourish yang qi of human body, contains abundant proteins and sugar, generates heat and warms abdomen, and can enhance cold resistance of human body. The black tea and the brown sugar are used together, so that the black tea not only can generate heat and warm the abdomen, but also can add nutrition and strengthen the body, and the black tea and the brown sugar have good synergistic effect.

(4) According to the invention, through the classifying and grading step, tea leaves are converted into three class-grade black tea of black powder tea, broken black tea and black tea, so that the efficient utilization of tea resources is promoted, and the color, aroma, taste, shape, quality and drinking value of the tea are also improved.

(5) The invention uses the special function of microwaves to dehydrate, sterilize and improve the fragrance, which not only can optimize the quality of the transformed black tea, but also can ensure the quality safety of the product.

(6) The old taste of the aged green tea is difficult to thoroughly remove, and the lotus leaf scenting technology is adopted, so that the lotus leaf scent is immersed into the black tea to be mixed with the black tea scent, and unique scent is generated.

(7) The process provided by the invention can realize mechanized and continuous production, remarkably improve the production efficiency, reduce the production cost, save energy and protect environment; the whole tea making process is completed in mechanical equipment, and the aroma raising technologies of electric heating for removing stale flavor, high-temperature drying, microwave sterilization and the like are applied, so that the quality safety of the product can be ensured.

Detailed Description

The invention will be further illustrated with reference to examples. It will be apparent that the described embodiments are some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

It should be noted that the electric heating dryer, the microwave tempering dehydrator, the stainless steel rolling machine and other devices used in the following examples are all commercially available from Zhejiang Sanyo mechanical company, and the specific working principles thereof are not described here. The cellulases and saccharifying enzymes used in the examples are commercially available from Henan Yangshao Biochemical engineering Co. The above-described apparatus and reagents are presented merely to illustrate the apparatus and reagent sources and compositions employed in the experiments of the present invention and to provide a thorough disclosure, and do not represent that the present invention could not be practiced with other reagents of the same type or provided by other suppliers.

Example 1

Example 1 is a process for making tea in spring, a process for making black tea using aged green tea, comprising the steps of:

s1, heating to remove ageing: heating aged green tea with 6CH13-20 electrothermal dryer, and maintaining at 130deg.C for 4min to remove stale;

s2, softening by adding water: adding 100 jin of aged green tea with old taste removed into 400 jin of warm water at 45 ℃ for soaking for 2 hours, and softening the aged green tea into wet tea after absorbing water;

s3, enzymatic pile fermentation: adding 5% cellulase into wet tea by oven-dried weight, placing on bamboo pad, piling into pyramid shape, piling for 8 hr to form enzymatic reaction, and promoting cellulose decomposition in aged tea to knead into strips.

S4, microwave dehydration: dehydrating, volatilizing and eliminating some harmful biological germs in the aged tea by using a 6CSW-80 microwave tempering dehydrator to obtain pretreated aged green tea;

s5, blending: the fresh tea leaves picked from the tea mountain are placed on an indoor bamboo mat to be dried for 3 cm in thickness, naturally withered for 2 hours, then placed under sunlight for withering for 1 hour, and after enzymatic reaction of the polyphenol oxidase of the fresh tea leaves is activated, the fresh tea leaves are transported into a withering tank, and withered for 2 hours by hot air at about 34 ℃ to obtain withered fresh tea leaves; weighing 100 kg of withered fresh leaves and 100 kg of pretreated aged green tea prepared in the step S4, and mixing to obtain mixed tea.

S6, mixing and primary kneading: delivering the mixed tea leaves to a 6CR-55 stainless steel rolling machine for primary rolling, lightly rolling for 10 minutes at one quarter of the pressurizing position of the rolling machine, and crushing tea cells and primarily forming strips;

s7, enzyme is added for re-kneading: adding 0.4% of saccharifying enzyme into the primarily-formed mixed tea, and kneading for 45 min. Wherein the kneading is carried out for 10min, the kneading cover is pressurized for one third of the kneading for 30 min, then the kneading is carried out for 5min without pressure, and when the breaking rate of the kneaded leaf cells reaches 85%, the kneading is basically formed into strips.

S8, deblocking and screening: screening the mixed tea leaves by using a 6 CYS-60 fresh block screening machine to ensure that the mixed tea leaves are fully dispersed and do not agglomerate;

s9, sugar adding fermentation: adding brown sugar 1% by mass into the mixed tea leaves after deblocking and sieving, stirring uniformly, performing natural fermentation at about 33 ℃ for 1.5 hours, keeping the humidity of a fermentation chamber at about 90%, and timely ventilating and supplying oxygen;

s10, enzymatic fermentation: adding 0.3% of saccharifying enzyme into the mixed tea after natural fermentation, stirring uniformly, and then carrying out enzymatic fermentation to obtain black tea; the temperature of the enzymatic fermentation is 34 ℃, the time is 2.5 hours, and the ambient humidity is about 85%. Fermenting the aged tea fully by enzymatic fermentation to turn red;

s11, drying: the method comprises the following steps of: firstly, hot air primary drying is carried out on black tea by a 6CHB-20 hot air dryer at the temperature of 125 ℃ to ensure that the water content is about 45%; then, blowing cold air into the black tea by using a 6CHB-20 type tea moisture regaining machine, cooling and remoistening, and blowing cold air for cooling to ensure that water on the surface of the primary drying leaves is lost, and the water in the primary drying leaves overflows so as to dry feet; finally, a 6CHB-100 dynamic dryer is used for hot air foot drying at 120 ℃ so that the water content of the black tea reaches about 8%, and foot drying is stopped.

S12, selecting stems: the dried black tea is picked by a 6CSX-180SE2 digital intelligent tea color selector, and sundries such as tea stalks, tea fruits and the like are removed;

s13, winnowing and impurity removal: performing air separation and impurity removal on black tea after color selection and stem selection by using a 6CEF-40 tea winnowing machine, and further blowing off tea slices, tea leaves, tea ash and impurities to obtain clean and even tea leaves;

s14, classifying and grading: classifying with a 6CHY-40 plane round sieve machine by using 12-hole and 6-hole sieves, wherein the tea leaves below the 12-hole sieve surface are black powder tea, the tea leaves above 12-6 holes are black broken tea, and the tea leaves above the 6-hole sieve surface are red raw tea;

s15, microwave aroma extraction: sterilizing and aroma improving the black powder tea, the broken black tea and the black crude tea at 105 ℃ by using a 6CSW-80 microwave machine; the high-temperature aroma extraction and microwave sterilization are carried out, so that the quality safety of the product is ensured, the water content of the black tea after aroma extraction is between 6%, and otherwise, the quality is influenced;

s16 lotus leaf scenting: respectively placing the minced black tea, broken black tea and crude black tea subjected to microwave aroma extraction into a stainless steel container, paving and stacking a layer of tea leaves and a layer of dried lotus leaf bags, and then scenting, wherein the stacking height of each layer of tea leaves is 30 cm; the scenting time is three days, and the peculiar faint scent of the lotus leaves is soaked into the black tea through the scenting, so that the lotus leaves form unique lotus-fragrance tea; removing lotus leaf bag after scenting, sealing and packaging with composite aluminum plastic bag to obtain air-permeable visible light, and keeping shelf life for two years to obtain final product.

Example 2

Example 2 was prepared in summer and autumn, and the procedure was the same as in example 1, except that the following partial operation conditions were different, because the temperature in summer and autumn was higher:

s1, heating to remove ageing: the working temperature of the electric heating dryer is 120 ℃, and the ageing removing time is 3min;

s2, softening by adding water: the temperature of the warm water is 45 ℃, and the soaking time is 1 hour;

s3, enzymatic pile fermentation: adding 0.5% cellulase into wet tea by oven-dried weight, placing on bamboo pad, piling into pyramid shape, piling for 6 hr to form enzymatic reaction, and promoting cellulose decomposition in aged tea to knead into strips.

S4, microwave dehydration: the same as in example 1;

s5, blending: the fresh tea leaves picked from the tea mountain are put on an indoor bamboo mat for airing with the thickness of 3 cm, naturally withered for 1 hour due to higher temperature in summer and autumn, then are put under sunlight for withering for 0.5 hour, and are transported into a withering tank after enzymatic reaction of polyphenol oxidase of the fresh tea leaves is activated, and are withered for 1.5 hours by hot air at the temperature of about 32 ℃ to obtain withered fresh tea leaves; weighing 100 kg of withered fresh leaves and 120 kg of pretreated aged green tea prepared in the step S4, and mixing to obtain mixed tea.

S6, mixing and primary kneading: the same as in example 1;

s7, enzyme is added for re-kneading: the amount of the saccharifying enzyme added was 0.3%, and the other operations were the same as in example 1.

S8, deblocking and screening: the same as in example 1;

s9, sugar adding fermentation: adding brown sugar with the mass of 1.5% into the mixed tea leaves subjected to deblocking and screening, stirring uniformly, naturally fermenting at the temperature of about 32 ℃ for 1 hour, keeping the humidity of a fermentation chamber at about 88%, and timely ventilating and supplying oxygen;

s10, enzymatic fermentation: adding 0.3% of saccharifying enzyme into the mixed tea after natural fermentation, stirring uniformly, and then carrying out enzymatic fermentation to obtain black tea; the temperature of the enzymatic fermentation is 33 ℃, the time is 2 hours, and the ambient humidity is about 90%. Fermenting the aged tea fully by enzymatic fermentation to turn red;

s11, drying: the method comprises the following steps of: firstly, hot air primary drying is carried out on black tea by a 6CHB-20 hot air dryer at the temperature of 125 ℃ to ensure that the water content is about 45%; then, blowing cold air into the black tea by using a 6CHB-20 type tea moisture regaining machine, cooling and remoistening, and blowing cold air for cooling to ensure that water on the surface of the primary drying leaves is lost, and the water in the primary drying leaves overflows so as to dry feet; finally, a 6CHB-100 dynamic dryer is used for hot air foot drying at 115 ℃ to lead the water content of the black tea to reach about 7 percent and stop foot drying.

S12, selecting stems: the same as in example 1;

s13, winnowing and impurity removal: the same as in example 1;

s14, classifying and grading: the same as in example 1;

s15, microwave aroma extraction: the aroma raising temperature is 100 ℃, and the water content of the black tea after aroma raising is about 6%;

s16 lotus leaf scenting: the same as in example 1.

The tea prepared in the above example 1 was subjected to quality detection, and the overall color, aroma, taste and shape were substantially similar to those of the black tea directly processed from fresh tea leaves, and the aroma and taste were better, but the soup color was less red and bright, slightly red and yellow, the leaf bottom had dark stripes, and the black piece could be considered as the quality characteristics of medium-grade black tea. The results are shown in Table 1 below, and the quality characteristics of the tea obtained in example 1

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Claims

1. A method for preparing black tea by aging green tea, which is characterized in that: the method comprises the following steps:

s1, heating to remove ageing: heating aged green tea to remove stale at 120-130deg.C;

s2, softening by adding water: adding aged green tea without old taste into warm water for soaking, and softening into wet tea after the aged green tea absorbs water;

s3, enzymatic pile fermentation: adding cellulase into the wet tea, and enzymatically piling for 6-8 hours;

s4, microwave dehydration: placing the aged green tea subjected to enzymatic pile fermentation into microwave dehydration equipment for microwave dehydration treatment to obtain pretreated aged green tea;

s5, blending: withering fresh tea leaves to obtain withered fresh leaves, and mixing the withered fresh leaves with the pretreated aged green tea prepared in the step S4 to obtain a mixture of 1: mixing the materials according to the mass ratio of (1-1.2) to obtain mixed tea;

s6, mixing and primary kneading: primarily twisting the mixed tea leaves to primarily strip the mixed tea leaves;

s7, enzyme is added for re-kneading: adding saccharifying enzyme into the primarily-formed mixed tea, and twisting again to enable the mixed tea to be basically formed into strips;

s9, sugar adding fermentation: adding brown sugar into the mixed tea leaves subjected to deblocking and screening, uniformly stirring, and then naturally fermenting;

s10, enzymatic fermentation: adding saccharifying enzyme into the mixed tea after natural fermentation, stirring uniformly, and then carrying out enzymatic fermentation to obtain black tea;

s11, drying: drying the black tea subjected to enzymatic fermentation to reduce the water content to 7-8%;

s12, selecting stems: selecting stems of the dried black tea by using a tea She Zhineng color sorter;

s13, winnowing and impurity removal: carrying out winnowing and impurity removal on black tea after color sorting to obtain clean and even tea;

s15, microwave aroma extraction: sterilizing and extracting fragrance of the black powder tea, the broken black tea and the black crude tea by using a microwave fragrance extracting machine;

s16 lotus leaf scenting: respectively placing the minced black tea, broken black tea and crude black tea subjected to microwave aroma extraction into a sealed container, and paving and stacking the minced black tea, the broken black tea and the crude black tea in a mode of wrapping a layer of tea leaves and a layer of dried lotus leaves, and then scenting; removing the lotus leaf bag after the scenting is finished, and then sealing and packaging various black tea to obtain the final product.

2. The method according to claim 1, characterized in that: in step S1, an electric heating dryer is adopted to heat the aged green tea to age.

3. The method according to claim 1, characterized in that: in the step S2, the temperature of the warm water is 40-50 ℃, and the soaking time is 1-2 hours.

4. The method according to claim 1, characterized in that: in step S4, the microwave dehydration device is a microwave tempering dehydrator.

5. The method according to claim 1, characterized in that: in step S5, the withering process includes the steps of: and (3) naturally withering the fresh tea leaves in a room temperature environment for 1-2 hours, then withering the fresh tea leaves in sunlight for 0.5-1 hour, and finally placing the fresh tea leaves withered in sunlight into a withering tank for hot air withering for 1-2 hours by using hot air at 32-34 ℃.

6. The method according to claim 1, characterized in that: in the step S7, the mass of the added saccharifying enzyme is 0.3-0.4% of the mass of the mixed tea; the step of re-twisting is as follows: firstly, lightly kneading for 8-12min, then, pressurizing and re-kneading for 25-35min, and finally, non-pressurizing and loosening and kneading for 4-6min.

7. The method according to claim 1, characterized in that: in the step S9, the addition amount of the brown sugar is 1-1.5% of the mass of the mixed tea; the temperature of the natural fermentation is 32-33 ℃, the time is 1-1.5 hours, the ambient humidity is 85-90%, and the natural fermentation is ventilated and supplied with oxygen in time.

8. The method according to claim 1, characterized in that: in the step S10, the adding amount of the saccharifying enzyme is 0.2-0.3% of the mass of the mixed tea; the temperature of the enzymatic fermentation is 33-34 ℃, the time is 2-2.5 hours, and the ambient humidity is 85-90%.

9. The method according to claim 1, characterized in that: in step S11, the drying process includes the steps of: firstly, hot air drying is carried out on black tea by a hot air dryer at the temperature of 125-130 ℃ to ensure that the water content of the black tea is 45-50%; then blowing cold air to the black tea by using a cooling and conditioning machine to make the surface water of the black tea emit and the internal water overflows; finally, using a hot air dryer to perform hot air foot drying at the temperature of less than or equal to 120 ℃ so that the water content of the black tea reaches 7-8%.