阅读说明：本技术 一种乌龙红茶的制作工艺 (Manufacturing process of oolong black tea ) 是由 王进财 龚晓森 许常达 于 2021-08-25 设计创作，主要内容包括：本发明公开了一种乌龙红茶的制作工艺,晒青通过专用的多功能摊平机可以对茶叶进行摊开和翻动晾晒,可以使茶叶充分均匀的萎凋,降低茶汤的苦涩味,增进醇和爽口；本发明生产工序中还采用了低温发酵技术、酶加工技术和二次加工方法,经过多次发酵和烘干有效保持了茶叶中的生物酶不被氧化,可使茶叶保留了一定的新鲜度,避免了活性酶氧化,从而避免有效成分被破坏,得到降低咖啡因的乌龙红茶,且茶叶经过多糖水解酶和单宁酶的浸提加工后,水浸出物和和茶黄素含量提高,能显著促进茶叶中有益成分的转化,并保持茶叶的活性物质以保证风味,提升茶叶的品质和附加价值。(The invention discloses a manufacturing process of oolong black tea, wherein the tea leaves can be spread, turned and aired through a special multifunctional spreading machine after being aired, so that the tea leaves can be fully and uniformly withered, the bitter taste of tea soup is reduced, and the tea soup is mellow and refreshing; the production process of the invention also adopts a low-temperature fermentation technology, an enzyme processing technology and a secondary processing method, biological enzymes in the tea are effectively kept from being oxidized after multiple times of fermentation and drying, certain freshness of the tea can be kept, and active enzyme oxidation is avoided, so that the effective components are prevented from being damaged, the oolong black tea with reduced caffeine is obtained, and after the tea is subjected to leaching processing of polysaccharide hydrolase and tannase, the contents of water extract and theaflavin are increased, the conversion of beneficial components in the tea can be remarkably promoted, the active substances of the tea are kept to ensure the flavor, and the quality and the added value of the tea are improved.)

1. A manufacturing process of oolong black tea is characterized by comprising the following steps: the method comprises the following steps:

(1) harvesting green: picking fresh leaves of tea trees, and leaving two or three leaves of the fresh leaves;

(2) and (3) drying in the sun: the tea leaf spreading machine comprises a rack (1) and a rotatable frame (2) rotatably mounted on the rack (1), wherein a foldable drying rack and a folding and unfolding driving mechanism are arranged on the rotatable frame (2), the foldable drying rack is formed by connecting and hinging a plurality of groups of interlayer screen plate units which are arranged in pairs in series, each interlayer screen plate unit comprises a U-shaped support frame (3) and two fixing nets (4), the two fixing nets (4) are respectively and fixedly mounted on two sides of the U-shaped support frame (3), an interlayer cavity (5) for placing tea leaves is formed between the two fixing nets (4), one end of the U-shaped support frame (3) forms a material inlet and outlet (6) communicated with the interlayer cavity (5), and the folding and unfolding driving mechanism is used for driving the interlayer screen plate units of the foldable drying rack to be vertically folded and horizontally unfolded, when the interlayer screen plate unit is in a vertical folding state, the material inlet and outlet (6) is arranged upwards in the vertical direction, tea leaves to be aired can be poured into the interlayer cavity (5) at the moment, or the angle of the rotatable frame (2) is adjusted to enable the material inlet and outlet (6) to face downwards, the aired tea leaves are poured out, when the interlayer screen plate unit is in a horizontal unfolding state, the material inlet and outlet (6) in the same group are mutually butted in the horizontal direction, the rotatable frame (2) can be swung to vibrate the tea leaves to realize flattening, the tea leaves are aired for 0.3-0.6h in the sun, and the tea leaves can be turned over for 5-30 times through the rotatable frame (2) in the period until the moisture in the tea leaves is 60% -80%, and the tea leaves are twisted by hands easily;

(3) rocking and cooling: spreading the tea leaves for cooling for 0.4-0.8 h by using the multifunctional spreading machine in an indoor environment, and then shaking the green by using a green shaking device;

(4) rolling: rolling the tea leaves after green shaking for 0.5-1.5 h by using a rolling device;

(5) and (3) uniform fermentation: spreading the rolled tea leaves, wherein the fermentation is to put the tea leaves into a fermentation chamber for fermentation for 5.0-8.0 h, the humidity of the fermentation chamber is 75-80%, the temperature is 26-35 ℃, and the tea leaves are spread to be 3-8 cm thick;

(6) primary drying: placing the tea leaves into a drying device to be baked for 1.0-2.0 h, wherein the baking temperature is 65-80 ℃ until the weight of water in the tea leaves is 35-45%;

(7) standing and fermenting at low temperature: screening and removing tea stalks, and then performing low-temperature fermentation to obtain fermented oolong black tea with caffeine reduced;

(8) leaching enzyme liquid: uniformly spraying a leaching liquor mixed solution containing 360-450 u/ml of polysaccharide hydrolase and 300-550 u/ml of tannase onto the tea leaves after low-temperature fermentation, wherein the weight ratio of the leaching liquor to the tea leaves is 1: 10-1: 8, and fermenting for twenty-four hours after mixing;

(9) secondary drying: and (3) drying the tea leaves in a drying device for 1.5 to 2.5 hours at the drying temperature of between 100 and 120 ℃ until the weight of water in the tea leaves is 5 to 8 percent.

2. A process of making oolong black tea as claimed in claim 1 wherein: the folding and unfolding driving mechanism comprises a synchronous driving mechanism, two belt driving mechanisms and two guide rail sliding block mechanisms, one belt driving mechanism and one guide rail sliding block mechanism form a pair, two pairs of mechanisms are respectively installed on two sides of a rotatable frame (2), the belt driving mechanism comprises a driving belt wheel (7), a driven belt wheel (8) and a driving belt (9) tightly sleeved on the two wheels, a left traction block (10) and a right traction block (11) are respectively and fixedly arranged on the upper section of the driving belt (9) and the lower section of the driving belt (9), a traction rope (12) is connected between the left traction block (10) and the right traction block (11), the guide rail sliding block mechanism comprises a linear guide rail (13) fixedly arranged between the upper section of the driving belt (9) and the lower section of the driving belt (9) and a plurality of sliding blocks (14) slidably installed on the linear guide rail (13), the left traction block (10) and the right traction block (11) are respectively and slidably installed at the left end and the right end of the linear guide rail (13), evenly spaced fixed distribution has on haulage rope (12) sliding block (14), the both ends of intermediate layer otter board unit correspond to rotate and install on both sides sliding block (14), synchronous drive mechanism includes linear drive motor, universal driving shaft, driving gear and driven gear, fixed mounting has on linear drive motor's the output the driving gear, the driving gear meshing is connected driven gear, driven gear fixed connection the universal driving shaft, the both ends of universal driving shaft respectively with both sides driving pulley (7) fixed connection.

3. A process of making oolong black tea as claimed in claim 2 wherein: the left end and the right end of the rotatable frame (2) are respectively provided with a rotating shaft (15) which is used for rotating and connecting the frame (1), the frame (1) is fixedly provided with a rotary driving motor (16) used for adjusting the angle, and the rotary driving motor (16) is fixedly connected with one of the rotating shafts (15).

4. A process of making oolong black tea as claimed in claim 2 wherein: the rolling device is positioned below the foldable drying rack and comprises a plurality of lifting supports (17), a plurality of elastic telescopic rods (18) are fixed on the lifting supports (17), and rolling wheels (19) are fixedly installed at the upper ends of the elastic telescopic rods (18).

5. A process of making oolong black tea as claimed in claim 2 wherein: the inner wall of the U-shaped support frame (3) is provided with a plurality of U-shaped slots for inserting and installing the fixing net (4) at intervals.

6. A process of making oolong black tea as claimed in any of claims 1 to 5 wherein: the foldable drying rack is characterized in that a chamber (20) for accommodating the foldable drying rack and a sealing turnover cover for sealing the chamber (20) are arranged on the rack (1), and a humidifier (21) and a heater (22) are arranged on the inner wall of the chamber (20).

7. A process of making oolong black tea as claimed in claim 6 wherein: the bottom both sides of cavity (20) are equipped with vent (23), and vent (23) are equipped with in proper order from outside to inside and install filter screen (24), valve (25) and fan (26).

8. A process of making oolong black tea as claimed in claim 1 wherein: in the step (7), the fermentation time is 6-8 hours, and the temperature is 25-27 ℃.

9. A process of making oolong black tea as claimed in claim 1 wherein: in the step (8), the enzymolysis temperature of the enzyme liquid leaching is 28-45 ℃.

10. A process of making oolong black tea as claimed in claim 1 wherein: the polysaccharide hydrolase is one or both of pectinase and cellulase, and the ratio of the pectinase to the cellulase is 7: 10 in proportion.

Technical Field

The invention relates to the technical field of tea processing, in particular to a manufacturing process of oolong black tea.

Background

Oolong tea, also known as green tea and semi-fermented tea, is a unique tea product with distinctive characteristics in several large Chinese teas. The oolong tea integrates the preparation methods of green tea and black tea, has the quality between that of the green tea and the black tea, has the strong and fresh taste of the black tea, has the fragrance of the green tea and has the reputation of 'green leaf red edging'. The oolong tea is usually semi-fermented tea, during the fermentation process, chemical substances contained in the tea are converted, the tea property is gradually milder, and the oolong tea has no great irritation to intestines and stomach, has good effects of nourishing and protecting the stomach, and has certain curative effects on aspects of reducing blood fat, reducing blood pressure, reducing blood sugar and the like. The black tea is fully fermented tea, and is processed in the processing process; the main chemical component of tea polyphenol in fresh tea leaves is subjected to a series of enzymatic chemical changes under the action of enzyme, and the tea polyphenol is oxidized and polymerized to form theaflavins and thearubigins with huge molecular weight. Thearubigins and theaflavins are characteristic substances of black tea, and the quality and style of the tea are influenced by the content of the thearubigins and the theaflavins. Meanwhile, thearubigins and theaflavins are the most main effective components in black tea, and the black tea shows good physiological activity. The conventional procedures of the conventional black tea manufacturing process comprise withering, rolling, fermenting and drying, in order to improve the tea aroma of the black tea and further improve the quality of the black tea, aroma raising treatment can be carried out after drying, so that the aroma and the taste concentration of the tea can be effectively improved, but the aroma raising treatment easily causes the tea to be burnt and influences the aroma of the tea; the content of thearubigin and theaflavin can be reduced, the tea quality is influenced, the liquor color of the tea can be browned and blackened, and free amino acids of the tea can be damaged. Therefore, the research and development of the unique black tea manufacturing process and processing equipment have wide application prospects.

Disclosure of Invention

The invention aims to solve the problems in the prior art and provides a preparation process of oolong black tea, which further extracts effective components of natural products and improves the quality of black tea.

The invention adopts the technical scheme for solving the technical problems that: a manufacturing process of oolong black tea comprises the following steps:

(1) harvesting green: picking fresh leaves of tea trees, and leaving two or three leaves of the fresh leaves;

(2) and (3) drying in the sun: the tea leaf spreading machine comprises a rack and a rotatable frame rotatably mounted on the rack, wherein a foldable drying rack and a folding and unfolding driving mechanism are arranged on the rotatable frame, the foldable drying rack is formed by connecting and hinging a plurality of groups of interlayer screen plate units which are arranged in pairs in series, each interlayer screen plate unit comprises a U-shaped support frame and two fixing nets, the two fixing nets are respectively and fixedly mounted on two sides of the U-shaped support frame, an interlayer cavity for placing tea leaves is formed between the two fixing nets, a material inlet and a material outlet communicated with the interlayer cavity are formed at one end of the U-shaped support frame, the folding and unfolding driving mechanism is used for driving the interlayer screen plate units of the foldable drying rack to be vertically folded and horizontally unfolded, and when the interlayer screen plate units are in a vertically folded state, the feeding and discharging ports are arranged upwards in the vertical direction, tea leaves to be aired can be poured into the interlayer cavity, or the angle of the rotatable frame is adjusted to enable the feeding and discharging ports to face downwards, the aired tea leaves are poured out, when the interlayer screen plate unit is in a horizontal unfolding state, the two feeding and discharging ports in the same group are mutually butted in the horizontal direction, the rotatable frame can be swung to vibrate the tea leaves to realize flattening, the tea leaves are aired for 0.3-0.6h in the sun, and the tea leaves can be turned for 5-30 times through the rotatable frame during the period until 60% -80% of water in the tea leaves is left, and the tea leaves are not easy to twist by hands;

(3) rocking and cooling: spreading the tea leaves for cooling for 0.4-0.8 h by using the multifunctional spreading machine in an indoor environment, and then shaking the green by using a green shaking device;

(4) rolling: rolling the tea leaves after green shaking for 0.5-1.5 h by using a rolling device;

(5) and (3) uniform fermentation: spreading the rolled tea leaves, wherein the fermentation is to put the tea leaves into a fermentation chamber for fermentation for 5.0-8.0 h, the humidity of the fermentation chamber is 75-80%, the temperature is 26-35 ℃, and the tea leaves are spread to be 3-8 cm thick;

(6) primary drying: placing the tea leaves into a drying device to be baked for 1.0-2.0 h, wherein the baking temperature is 65-80 ℃ until the weight of water in the tea leaves is 35-45%;

(7) standing and fermenting at low temperature: screening and removing tea stalks, and then performing low-temperature fermentation to obtain fermented oolong black tea with caffeine reduced;

(8) leaching enzyme liquid: uniformly spraying a leaching liquor mixed solution containing 360-450 u/ml of polysaccharide hydrolase and 300-550 u/ml of tannase onto the tea leaves after low-temperature fermentation, wherein the weight ratio of the leaching liquor to the tea leaves is 1: 10-1: 8, and fermenting for twenty-four hours after mixing;

(9) secondary drying: and (3) drying the tea leaves in a drying device for 1.5 to 2.5 hours at the drying temperature of between 100 and 120 ℃ until the weight of water in the tea leaves is 5 to 8 percent.

In order to further improve the structure, the folding and unfolding driving mechanism comprises a synchronous driving mechanism, two belt driving mechanisms and two guide rail sliding block mechanisms, one belt driving mechanism and one guide rail sliding block mechanism form a pair, two pairs of mechanisms are respectively arranged at two sides of a rotatable frame, the belt driving mechanism comprises a driving belt wheel, a driven belt wheel and a driving belt tightly sleeved on two wheels, a left traction block and a right traction block are respectively and fixedly arranged on the upper section of the driving belt and the lower section of the driving belt, a traction rope is connected between the left traction block and the right traction block, the guide rail sliding block mechanism comprises a linear guide rail fixedly arranged between the upper section of the driving belt and the lower section of the driving belt and a plurality of sliding blocks slidably arranged on the linear guide rail, the left traction block and the right traction block are respectively and slidably arranged at the left end and the right end of the linear guide rail, and the sliding blocks are uniformly and fixedly distributed on the traction rope at intervals, the two ends of the interlayer screen plate unit are correspondingly rotatably installed on the sliding blocks on the two sides, the synchronous driving mechanism comprises a linear driving motor, a linkage shaft, a driving gear and a driven gear, the driving gear is fixedly installed on the output end of the linear driving motor, the driving gear is meshed with the driven gear, the driven gear is fixedly connected with the linkage shaft, and the two ends of the linkage shaft are respectively fixedly connected with the driving belt wheels on the two sides.

Further perfecting, both ends are equipped with one respectively and are used for rotating the rotation axis of connecting the frame about rotatable frame, fixed mounting has the rotary driving motor who is used for angle regulation in the frame, rotary driving motor and one of them axis of rotation fixed connection.

Further perfecting, the rolling device is located below the foldable drying rack and comprises a plurality of lifting supports, a plurality of elastic telescopic rods are fixed on the lifting supports, and rolling wheels are fixedly mounted at the upper ends of the elastic telescopic rods.

Further perfection, the inner wall interval of U-shaped support frame is equipped with many and is used for pegging graft the U-shaped slot of installation the fixed network.

Further perfection, the rack is provided with a chamber for accommodating the foldable drying rack and a sealing turnover cover for sealing the chamber, and the inner wall of the chamber is provided with a humidifier and a heater.

Further perfect, the bottom both sides of cavity are equipped with the vent, and the vent is equipped with from outside to inside in proper order and installs filter screen, valve and fan.

Further perfecting, in the step (7), the fermentation time is 6-8 hours, and the temperature is 25-28 ℃.

Further perfecting, wherein in the step (8), the enzymolysis temperature of enzyme liquid leaching is 28-45 ℃.

Further perfected, the polysaccharide hydrolase is one or both of pectinase and cellulase in a ratio of 7: 10 in proportion.

The invention has the beneficial effects that: (1) the sun-drying is a key process for making a foundation in the whole tea making process, the tea leaves can be spread, turned and dried by a multifunctional spreading machine, the tea leaves can be fully and uniformly withered, part of water in the fresh leaves is lost, the concentration of leaf cell juice is increased, the activities of tea polyphenol oxidase and other hydrolase are enhanced, the content of tea polyphenol is properly reduced, the bitter taste of tea soup is reduced, and the mellow and refreshing taste is promoted;

(2) the production process adopts a low-temperature fermentation technology, so that the biological enzymes in the tea leaves are effectively kept from being oxidized, certain freshness of the tea leaves can be kept, and the active enzyme oxidation is avoided, so that the active ingredients are prevented from being damaged, the caffeine oolong black tea is reduced, the uncomfortable hazards such as palpitation caused by drinking a large amount of tea in a short time can be avoided, people who have stomach diseases and heart diseases and are afraid of drinking the tea can enjoy the benefits of drinking the tea, and a proper amount of tea can be drunk to achieve the purposes of strengthening the spleen, stomach and cardiovascular health;

(3) by adopting the method, after the tea is leached and processed by polysaccharide hydrolase and tannase, the polysaccharide hydrolase can promote the damage of the leaf tissue, part of insoluble substances are separated, the action of oxidase is enhanced, the tannase can hydrolyze tea milk condensate to enhance the taste, can hydrolyze gallocatechin to reduce the bitter taste, improve the leaching rate, show that the contents of water extract and theaflavin after enzyme processing are improved, can obviously promote the conversion of beneficial components in the tea, and keep the active substances of the tea to ensure the flavor, improve the quality and the added value of the tea, and have important effect on increasing the economic benefit of tea industry;

(4) the invention relates to a low-temperature enzyme method secondary processing method of tea, which can further improve the quality of black tea through multiple fermentation and drying, effectively improve the aroma and the taste concentration of the tea, and prevent the tea from being burnt to influence the aroma of the tea; the content of thearubigin and theaflavin is not reduced.

Drawings

FIG. 1 is a flow chart of a fabrication process of the present invention;

fig. 2 is a schematic structural view of the multifunctional spreader when unfolded;

FIG. 3 is a schematic structural view of a folding and unfolding driving mechanism;

description of reference numerals: 1. the device comprises a rack, 2, a rotatable frame, 3, a U-shaped support frame, 4, a fixed net, 5, an interlayer cavity, 6, a feeding and discharging port, 7, a driving belt wheel, 8, a driven belt wheel, 9, a driving belt, 10, a left traction block, 11, a right traction block, 12, a traction rope, 13, a linear guide rail, 14, a sliding block, 15, a rotating shaft, 16, a rotary driving motor, 17, a lifting support, 18, an elastic telescopic rod, 19, a kneading wheel, 20, a cavity, 21, a humidifier, 22, a heater, 23, a ventilation opening, 24, a filter screen, 25, a valve, 26 and a fan.

Detailed Description

The invention will be further described with reference to the accompanying drawings in which:

referring to figure 1: the preparation process of the oolong black tea in the embodiment comprises the following steps:

(1) harvesting green: picking fresh leaves of tea trees, and leaving two or three leaves of the fresh leaves;

(2) and (3) drying in the sun: the tea leaf spreading machine comprises a rack 1 and a rotatable frame 2 rotatably mounted on the rack 1, wherein a foldable drying rack and a folding and unfolding driving mechanism are arranged on the rotatable frame 2, the foldable drying rack is formed by connecting and hinging a plurality of groups of interlayer screen plate units which are arranged in pairs in series, each interlayer screen plate unit comprises a U-shaped support frame 3 and two fixing screens 4, the two fixing screens 4 are respectively and fixedly mounted on two sides of the U-shaped support frame 3, an interlayer cavity 5 for placing tea leaves is formed between the two fixing screens 4, one end of the U-shaped support frame 3 is provided with a material inlet and outlet 6 communicated with the interlayer cavity 5, and the folding and unfolding driving mechanism is used for driving the interlayer screen plate units of the foldable drying rack to be vertically folded and horizontally unfolded, when the interlayer screen plate unit is in a vertical folding state, the material inlet and outlet 6 is arranged upwards in the vertical direction, tea leaves to be aired can be poured into the interlayer cavity 5, or the angle of the rotatable frame 2 is adjusted to enable the material inlet and outlet 6 to face downwards, the aired tea leaves are poured out, when the interlayer screen plate unit is in a horizontal unfolding state, the material inlet and outlet 6 of the same group are mutually butted in the horizontal direction, at the moment, the rotatable frame 2 can be swung to vibrate the tea leaves to realize flattening, the tea leaves are aired in the sun for 0.3-0.6h, the tea leaves can be turned over for 5-30 times through the rotatable frame 2 in the period until the moisture in the tea leaves is 60% -80%, and the tea leaves are not easy to break by hand;

the sun-drying is a key process for making a foundation in the whole tea making process. When the sun-drying is insufficient, the water content of the tea leaves is excessive, a few leaves can become soft, and most leaves are in a tension state, so that the following problems can be caused: the finished tea has more green strips; the taste is bitter and astringent and not fresh; the fragrance contains green smell; the leaf bottom is green. Excessive sunning can cause the blade to lose water excessively, and some tender leaves can become red and wrinkle, and the blade can not restore the tension state when leading to the green-sunning, also can appear some quality problems: the finished tea strip rope is light and floating; stuffy air appears; the tea soup is green; the finished tea has dark red color and luster and is not oily. Uneven sunning degree can cause the appearance of the finished tea to be stringy, the color of the finished tea to be miscellaneous and uneven.

The multifunctional tea leaf spreading machine can spread tea leaves and turn over and dry the tea leaves for multiple times, so that the tea leaves can be fully and uniformly withered, fresh leaves lose part of water, the concentration of leaf cell juice is increased, the activity of tea polyphenol oxidase and other hydrolase is enhanced, the content of tea polyphenol is properly reduced, the bitter taste of tea soup is reduced, and the tea soup is improved to be mellow and tasty. The multifunctional spreading machine can improve the spreading and turning effects of tea leaves, improve the sunning quality of the tea leaves, reduce the labor cost, improve the working efficiency of the sunning, and solve the technical problems of uneven spreading, untimely turning, large sunning labor capacity and the like of the tea leaves during manual sunning. According to the variety and the water content of the fresh leaves, a tea maker properly adjusts the sun-light irradiation angle, the sun-light irradiation time and the sun-light irradiation degree of the sunning through a multifunctional spreading machine according to the weather, the temperature and the like of the day, so that the fresh leaves are properly and uniformly withered, the color, the fragrance and the taste of single tea are excited, and a good foundation is laid for the formation of high-quality black tea;

(3) rocking and cooling: spreading the tea leaves for cooling for 0.4-0.8 h by using the multifunctional spreading machine in an indoor environment, and then shaking the green by using a green shaking device; the green tea leaf shaking is a process in the tea leaf making process, on one hand, the transportation function of a leaf tip tissue is enhanced through mechanical movement force to coordinate flavor development substances of tea soup, on the other hand, leaf cells are damaged through mechanical friction force, tea polyphenol is subjected to enzymatic oxidation to induce aroma, and the movement force and the friction force are coordinated and matched to form the unique aroma, high taste and mellow quality of tea. The left end and the right end of a rotatable frame 2 on the multifunctional spreading machine are respectively provided with a rotating shaft 15 which is used for being rotatably connected with the rack 1, a rotary driving motor 16 used for adjusting the angle is fixedly installed on the rack 1, and the rotary driving motor 16 is fixedly connected with one of the rotating shafts 15. The rotary driving motor 16 can drive after the circular telegram rotatable frame 2 carries out positive and negative upset and rotates, drives tealeaves on the collapsible sunning frame and shakes blue or green, and the system teachers can in time adjust the degree of shaking blue or green according to the degree of drying in the sun blue or green, and light then heavily shakes, and the heavy then gently shakes of drying in the sun blue or green degree of discordant tealeaves mixes and shakes blue or green and cause to shake blue or green and shake and become less than even, and the leaf "becomes red" inadequately.

(4) Rolling: rolling the tea leaves after green shaking for 0.5-1.5 h by using a rolling device; rolling is a molding process of primary processing of oolong tea, and the rolling forms a tightly curved shape and affects the improvement of the inner quality. The tea strips can be rolled up by rolling, the volume is reduced, a foundation is laid for frying the tea strips to be dry, and the tissue of the tea leaves and the material are properly damaged. The rolling device is positioned below the foldable drying rack and comprises a plurality of lifting supports 17, a plurality of elastic telescopic rods 18 are fixed on the lifting supports 17, and rolling wheels 19 are fixedly installed at the upper ends of the elastic telescopic rods 18. After green tea leaves are shaken, the lifting support 17 rises under the driving of the lifting cylinder, the kneading wheel 19 is pressed on the fixed net 4 through the elastic telescopic rod 18 to cause the volume change of the interlayer cavity 5, when the rotatable frame 2 swings forwards and backwards, and the elastic telescopic rod 18 elastically stretches, the kneading wheel 19 can roll on the fixed net 4, and the kneading effect on the tea leaves is further improved.

(5) And (3) uniform fermentation: spreading the rolled tea leaves, wherein the fermentation is to put the tea leaves into a fermentation chamber for fermentation for 5.0-8.0 h, the humidity of the fermentation chamber is 75-80%, the temperature is 26-35 ℃, and the tea leaves are spread to be 3-8 cm thick; during this time, the biological enzymes in the tea begin to work, converting the polyphenols into theaflavin, thearubigin, etc., so that the tea is full of red light, and the color of the tea turns yellow-red after the light fermentation is completed. The black tea is slightly fermented, so that the black tea has sweet and refreshing throat-moistening effects of white tea and high fragrance of oolong tea besides sweet and moistening taste of the traditional black tea.

(6) Primary drying: placing the tea leaves into a drying device to be baked for 1.0-2.0 h, wherein the baking temperature is 65-80 ℃ until the weight of water in the tea leaves is 35-45%; in order to enable the black tea to have the characteristic of high fragrance, incomplete non-auxiliary heating fermentation (light fermentation) is adopted during fermentation, and primary drying without enzyme deactivation is carried out in the later period so as to be different from the baking of the traditional black tea; that is, the tea prepared by the process has sweet (fresh degree) and high fragrance (aroma) of oolong, and has the color and luster of black tea, and the color and luster of tea soup are different from yellow to red.

(7) Standing and fermenting at low temperature: screening and removing tea stalks, and then performing low-temperature fermentation to obtain fermented oolong black tea with caffeine reduced; the fermentation time is 6-8 hours, and the temperature is 25-28 ℃. The low-temperature fermentation is to use microorganisms to perform fermentation at a relatively low temperature, so that the propagation of the microorganisms can be better controlled under the low-temperature condition, the fermentation is milder and more stable, and the tea can achieve better texture and flavor by prolonging the fermentation time of the tea.

(8) Leaching enzyme liquid: uniformly spraying a leaching liquor mixed solution containing 360-450 u/ml of polysaccharide hydrolase and 300-550 u/ml of tannase onto the tea leaves after low-temperature fermentation, wherein the weight ratio of the leaching liquor to the tea leaves is 1: 10-1: 8, and fermenting for twenty-four hours after mixing; the enzymolysis temperature of enzyme liquid extraction is 28-45 ℃. The polysaccharide hydrolase is one or both of pectinase and cellulase, and the ratio of the pectinase to the cellulase is 7: 10 in proportion. The polysaccharide hydrolase can promote the destruction of leaf tissues, separate partial insoluble substances, enhance the action of oxidase, hydrolyze tea milk condensate by tannase to enhance taste, hydrolyze gallocatechin to reduce bitterness, improve extraction rate, show that the content of water extract and theaflavin after enzyme processing is improved, can obviously promote the conversion of beneficial ingredients in tea, maintain the active substances of the tea to ensure flavor, improve the quality and added value of the tea, and play an important role in increasing the economic benefit of tea industry.

(9) Secondary drying: and (3) drying the tea leaves in a drying device for 1.5 to 2.5 hours at the drying temperature of between 100 and 120 ℃ until the weight of water in the tea leaves is 5 to 8 percent. Traditionally, drying is carried out by baking, and the baking process is equivalent to killing enzyme activity in the tea. The black tea of the invention is completely fermented after the second low-temperature fermentation, and enzyme deactivation operation is required after the complete fermentation. The tea leaves are baked for the second time to enable the surface shape of the tea leaves to be fixed until the tea stems of the tea leaves are easy to break, the obtained tea leaves are twisted into fine powder by hands, and the black tea is dark and smooth in color and has strong fruit fragrance.

As shown in fig. 3, the folding and unfolding driving mechanism includes a synchronous driving mechanism, two belt transmission mechanisms and two rail slider mechanisms, one belt transmission mechanism and one rail slider mechanism form a pair, two pairs of mechanisms are respectively installed at two sides of the rotatable frame 2, the belt transmission mechanism includes a driving pulley 7, a driven pulley 8 and a transmission belt 9 tightly sleeved on two pulleys, a left traction block 10 and a right traction block 11 are respectively and fixedly installed on the transmission belt 9 of the upper and lower sections, a traction rope 12 is connected between the left traction block 10 and the right traction block 11, the rail slider mechanism includes a linear guide rail 13 fixedly installed between the upper and lower sections of the transmission belt 9 and a plurality of sliding blocks 14 slidably installed on the linear guide rail 13, the left traction block 10 and the right traction block 11 are respectively and slidably installed at the left and right ends of the linear guide rail 13, the synchronous driving mechanism comprises a linear driving motor, a linkage shaft, a driving gear and driven gears, the driving gear is fixedly mounted at the output end of the linear driving motor, the driving gear is meshed with the driven gears, the driven gears are fixedly connected with the linkage shaft, and the two ends of the linkage shaft are respectively fixedly connected with the driving belt wheels 7 at the two sides. When the sandwich screen plate unit is used, the linear driving motor drives the driving belt wheels 7 on the two sides to rotate forwards and backwards through the driving gear, the driven gear and the linkage shaft, when the sandwich screen plate unit is in a folded state, the driving belt wheels 7 rotate forwards, the driving belt wheels 9 drive the left traction block 10 and the right traction block 11 to move away from each other and respectively move towards the left side and the right side, so that the traction ropes 12 are tensioned, the uniform interval distribution of the sliding blocks 14 on the linear guide rail is realized, and the sandwich screen plate unit is changed from the folded state to a horizontal unfolded state; when the folding is needed, the driving belt wheel 7 rotates reversely, the left traction block 10 and the right traction block 11 are driven to approach to the middle through the driving belt 9, and the sliding block 14 is pushed to the middle, so that the sandwich screen plate unit is changed into a folding state from horizontal unfolding. The inner wall interval of U-shaped support frame 3 is equipped with many and is used for the installation of pegging graft the U-shaped slot of fixed network 4 conveniently adjusts the distance between two fixed networks 4, adjusts the thickness that tealeaves was opened, was all piled.

The rack 1 is provided with a chamber 20 for accommodating the foldable drying rack and a sealing flip cover for sealing the chamber 20, and the inner wall of the chamber 20 is provided with a humidifier 21 and a heater 22. Humidifier 21 may control the ambient humidity within chamber 20 so that chamber 20 may correspond to a fermentation chamber. The heater 22 is a high color temperature and strong ultraviolet lamp, which simulates the sun rays and temperature to perform indoor blue-green drying. In tea picking seasons, clear and rainy days are usually encountered on mountains, the quality of finished tea is greatly influenced if the tea cannot be dried in the sun in time after being picked, and the quality of the tea is also reduced if the ageing of picked tip buds is delayed. Therefore, in the production process, the problem of making tea at night can be solved by sunning the tea leaves by the artificial light source, the benefit is greatly improved, and meanwhile, the optimal time period for picking tea in the afternoon can be utilized, and the working time is prolonged. Two sides of the bottom of the chamber 20 are provided with vents 23, and the vents 23 are sequentially provided with a filter screen 24, a valve 25 and a fan 26 from outside to inside. When tea needs to be spread for cooling or air-dried, the sealing turnover cover can be opened, the fan 26 is started to work, external air is sucked from the ventilation opening 23, then the air flow blows the tea on the drying rack from bottom to top, and water control of the tea in spreading for cooling or air-drying is achieved.

While the invention has been shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the appended claims.