A continuous production line for preparing yeast red tea by biological fermentation

Abstract

The application discloses a kind of continuous production line for preparing yeast black tea by biological fermentation, including quantitative impurity removal feeder conveyor, withering fermentation machine, kneading and twisting block fermentation machine and hot air drying aroma and vacuum freeze drying all-in-one machine.By this production line, the continuous processing of yeast black tea can be realized, and the temperature of each step in tea processing can be accurately controlled, thereby reducing the loss of polyphenol oxidase activity in tea, and completing the final drying of tea by freeze-drying, and retaining a higher activity of polyphenol oxidase.Therefore, the yeast black tea processed by this production line not only tastes good, but also can be used for fermentation with other plants, and the fermentation of other plants is promoted by polyphenol oxidase in tea, thereby used for the production and processing of composite black tea.It can be widely applied in the field of black tea processing technology.

Description

Technical Field

[0001] This invention relates to the field of tea processing technology, and in particular to a continuous production line for preparing yeast black tea using biological fermentation. Background Technology

[0002] In recent years, the development of compound black tea has been rapid, mainly including kudzu leaf black tea, ginkgo black tea, and chrysanthemum leaf black tea. Current processes for these compound black teas involve fermenting tea leaves with other plants, utilizing the fermentation enzymes in the tea leaves to promote the fermentation of the other leaves, thus producing compound black tea. Since the harvesting time of other plant leaves is not entirely the same as that of tea leaves, there is a need to develop a fermented black tea that can be added during the harvesting of other plant leaves, acting as yeast and utilizing the polyphenol oxidase in the tea leaves to promote the fermentation of the other plant leaves. However, the polyphenol oxidase (PPO) activity in the safflower produced by existing black tea processing technology and equipment is very low, making it difficult to drive the fermentation of other plants and produce a high-quality compound black tea with excellent color, aroma, taste, and appearance. To solve the problem of low polyphenol oxidase activity in existing finished black tea, which makes it difficult to promote the fermentation of other plants, it is necessary to change the existing black tea processing technology and equipment, and develop a completely new processing production line to ensure the taste of the black tea while maximizing the activation and preservation of polyphenol oxidase activity in the tea leaves, and enabling long-term storage for subsequent use in the fermentation of other plants. Summary of the Invention

[0003] The purpose of this invention is to provide a continuous production line for preparing yeast black tea using biological fermentation, which solves the problem that the polyphenol oxidase activity of black tea obtained from traditional black tea processing equipment is low, making it difficult to drive the mixed fermentation of other plant flowers and leaves to prepare compound black tea.

[0004] The technical solution adopted by the present invention to solve its technical problem is: a continuous production line for preparing yeast black tea by biological fermentation, including a quantitative impurity removal feeding conveyor, a withering fermentation machine, a kneading and de-clumping fermentation machine, and an integrated machine for hot air drying, aroma enhancement and vacuum freeze drying.

[0005] To achieve continuous processing of the seven steps in preparing black tea yeast—quantitative impurity removal, photothermal withering, enzyme-added steaming and oxygenation rolling, de-clumping and material distribution, dual-enzyme bio-fermentation, hot air aroma enhancement and initial drying, and vacuum freeze-drying—a quantitative impurity removal feeding conveyor, withering fermentation machine, rolling and de-clumping fermentation machine, and hot air drying and aroma enhancement and vacuum freeze-drying integrated machine are connected sequentially. Fresh tea leaves for preparing yeast black tea first pass through the quantitative impurity removal feeding conveyor, where they are weighed and then cleaned of dust, sand, small insects, insect eggs, debris, hair, fibers, broken flowers and leaves, metal, and other impurities via the impurity removal device on the conveyor belt. They are then fed upwards into the photothermal withering layer of the withering fermentation machine for high-temperature, medium-temperature, and low-temperature segmented photothermal withering. After completing the photothermal withering process, the withered buds and leaves are then fed into the lower photothermal steam fermentation layer, where they undergo low-temperature, medium-temperature, and high-temperature three-stage photothermal steam fermentation using the polyphenol oxidase contained within. After completing photothermal steam fermentation, the tea buds and leaves are fed into a kneading and de-clumping fermentation machine via an elevator. First, exogenous enzymes are added for enzymatic and oxygen-enriched kneading. The kneaded tea clumps, after this process, are de-clumped by a de-clumping drum before entering a fermentation tank for dual-enzyme bio-fermentation with polyphenol oxidase and exogenous enzymes. After this dual-enzyme bio-fermentation, the buds and leaves are conveyed by an elevator to the hot air initial drying and aroma-enhancing drum of a hot air drying and aroma-enhancing integrated machine. Hot air is first used to dissipate any "fermented odors," initially drying the moisture in the tea leaves and enhancing the tea and floral aromas. Then, the leaves are fed into a vacuum freeze dryer through the outlet, where a vacuum of 25-30 Pa and a low temperature of -10 to -16°C are used for vacuum freeze drying to produce yeast-infused black tea.

[0006] To ensure clean tea leaves are quantitatively fed into the withering and fermentation machine for the production of yeast-based black tea, the quantitative impurity-removing feeding conveyor includes a feeding hopper, a weighing device, an impurity removal device, and an impurity-removing conveyor belt. Specifically, the feeding hopper is a stainless steel, funnel-shaped structure positioned at the front end of the impurity-removing conveyor belt, allowing the tea leaves to be weighed within the hopper and then laid onto the conveyor belt. The weighing device is an electronic induction weigher installed inside the feeding hopper to achieve quantitative withering, thus improving withering quality. The impurity removal device includes an electromagnetic roller and a suction hood, installed at the discharge end of the impurity-removing conveyor belt to remove dust, fibers, hair, broken leaves, and metal debris from the tea leaves during the discharge process. Specifically, the impurity removal conveyor belt is an inclined conveyor belt with an 8-10 mesh stainless steel screen. It transports fresh tea leaves to the photothermal withering layer of the withering fermentation machine, and during the transport process, the screen removes mud, small insects, insect eggs, and other debris, ensuring the tea leaves are cleaned before withering. The technical benefits of using a quantitative impurity removal feeding conveyor are as follows: Utilizing electromagnetic rollers, a suction hood, and the impurity removal conveyor belt, dust, mud, small insects, insect eggs, fibers, hair, broken leaves, and metal debris carried in the fresh leaves can be removed. This ensures the cleaned tea leaves are quantitatively fed into the photothermal withering layer of the withering fermentation machine for photothermal withering, guaranteeing the quality and safety of the tea.

[0007] To improve the quality of photothermal withering, the photothermal withering layer of the withering fermentation machine is divided into three withering chambers: high-temperature, medium-temperature, and low-temperature. Fresh tea leaves are moved step-by-step on a stainless steel mesh conveyor belt through the high-temperature withering chamber → medium-temperature withering chamber → low-temperature withering chamber for segmented photothermal withering. First, the leaves are moved to the high-temperature withering chamber, where a temperature of approximately 41℃ enhances the activity of polyphenol oxidase, causing the buds and leaves to lose water and wilt, resulting in a reddish leaf color. Then, they are moved to the medium-temperature withering chamber, where a temperature of approximately 36℃ stabilizes the activity of polyphenol oxidase, promoting the enzymatic transformation of starch, protein, cellulose, and other substances in the fresh tea leaves, resulting in a sweet floral aroma. Finally, they are moved to the low-temperature withering chamber, where a temperature of approximately 32℃ weakens the activity of polyphenol oxidase, preventing over-withering, excessive water loss, and leaf dryness. To overcome the technical obstacle of using coarse, mature tea buds and leaves for yeast-based black tea production, which have well-developed palisade tissue and thick cuticles, making photothermal withering difficult, a stainless steel spiked leaf-equalizing roller is installed in the feeding trough of the photothermal withering layer. This roller rotates clockwise, evenly spreading the coarse, mature tea buds and leaves onto the screen conveyor belt while simultaneously piercing the cuticle layer, allowing photothermal light to penetrate deep into the cells for withering. Dividing the photothermal withering layer into three withering chambers (high temperature, medium temperature, and low temperature) for segmented photothermal withering produces the following effects: it effectively enhances, stabilizes, and weakens the activity of polyphenol oxidase, promotes the dissipation of grassy odors and the formation of aromatic substances, and improves the withering quality of the buds and leaves.

[0008] To improve the quality of photothermal steam fermentation, the photothermal steam fermentation layer of the withering fermentation machine is divided into three fermentation chambers—low temperature, medium temperature, and high temperature—using telescopic partitions. To address the challenge of fermenting coarse, mature tea buds with well-developed palisade tissue and a thick cuticle, steam nozzles are installed in the feed and discharge troughs of the photothermal steam fermentation layer. Utilizing 40℃ steam, this process both heats and ferments the coarse, mature fresh leaves after photothermal withering, and further breaks down the cell structure of the tea buds, allowing the photothermal heat to penetrate deep into the cells and activate polyphenol oxidase for enzymatic fermentation. After photothermal withering, the tea leaves are conveyed on a stainless steel screen conveyor belt, undergoing segmented fermentation by moving gradually through the "low temperature fermentation chamber → medium temperature fermentation chamber → high temperature fermentation chamber." First, the tea leaves are moved to a low-temperature fermentation chamber, where the activity of polyphenol oxidase is stimulated by light and heat at around 31°C. Then, they are moved to a medium-temperature fermentation chamber, where the activity of polyphenol oxidase is enhanced by light and heat at around 38°C. Finally, they are moved to a high-temperature fermentation chamber, where the fermentation kinetics of polyphenol oxidase are enhanced by steam at around 44°C, resulting in a large amount of enzymatic fermentation products. The technical effects of dividing the light-heat steam fermentation layer into three fermentation chambers (low-temperature, medium-temperature, and high-temperature) for segmented fermentation include: stimulating, enhancing, and increasing the fermentation kinetics of polyphenol oxidase, promoting the formation of large amounts of tea polyphenols, caffeine, amino acids, and other substances in the buds and leaves, and especially strengthening the oxidation, polymerization, and condensation reactions of catechins to form theaflavins, thearubigins, and theabrownins. The fermentation quality is superior to that of conventional black tea fermentation processes, which is beneficial for producing high-quality yeast-fermented black tea.

[0009] To facilitate the addition of exogenous enzymes during rolling and overcome the technical obstacles of coarse, old tea buds and leaves with high cellulose content and hard texture, making them difficult to roll into strips, the rolling drum and lid of the rolling machine are made of pine wood, while the rolling disc and its ribs are made of nano-ceramic material. An enzyme additive, an oxygen supply pipe, and a hot / cold air pipe are added to the lid to create an enzyme-added, oxygen-infused, and temperature-controlled wooden rolling machine. During rolling, exogenous biological enzymes can be added using the enzyme additive, oxygen can be supplied through the oxygen supply pipe, and the hot / cold air pipe can regulate the temperature for constant-temperature rolling, thus promoting efficient oxidative hydrolysis reactions between polyphenol oxidase and exogenous biological enzymes. The technical effects of using this enzyme-added, oxygen-infused wooden rolling machine are: it not only utilizes exogenous biological enzymes to decompose cellulose and soften the leaf texture, facilitating rolling into strips, but also utilizes polyphenol oxidase for oxidative hydrolysis reactions to convert and transform into a large amount of pectin, tea polysaccharides, theanine, and aromatic substances, optimizing the quality of yeast-treated black tea. It also uses wood and ceramic materials, which will not antagonize metal materials, and is conducive to the efficient enzymatic hydrolysis of polyphenol oxidase and exogenous enzymes, accelerating the reddening of buds and leaves, so as to form the excellent quality of red leaves, red soup and sweet aroma.

[0010] To quickly break up clumps of rolled tea, the de-clumping roller includes an inclined roller body. Inside the roller body is a screening cage that rotates with the roller body. One end of the screening cage has a tea inlet, and the other end is closed. One end of the roller body has a outlet. Inside the screening cage are de-clumping rollers that move relative to the screening cage. Each de-clumping roller is equipped with a dispersing rod. The surface of the screening cage also has a set of discharge holes through which the broken-up tea leaves fall into the roller body. The discharge holes are elongated structures adapted to the shape of the tea leaves. The tea clumps are continuously broken up by the de-clumping rollers and fall through the discharge holes. If a tea clump cannot fall through the discharge holes, it is broken up again, ensuring thorough de-clumping.

[0011] To achieve antagonistic dual-enzyme bio-fermentation, the fermentation tank is designed with a double-layer structure. The inner wall is made of cedar wood, and the outer wall is an insulation layer of nano-quartz material. The bottom of the tank uses a 20-mesh nano-bamboo charcoal fiber conveyor belt to facilitate metal-free de-clustering and dual-enzyme bio-fermentation. To improve fermentation efficiency and quality, the fermentation tank is equipped with three U-shaped supports, each fitted with a quartz infrared electric heat lamp, hot air pipe, and atomizing humidification nozzle. This allows for photothermal steam dual-enzyme fermentation of the buds and leaves after enzyme addition, kneading, and de-clustering. For convenient closed and open fermentation, a nano-bamboo charcoal fiber outer cover is laid on the U-shaped supports. This allows for closed dual-enzyme fermentation, which enhances the bio-fermentation dynamics of polyphenol oxidase, accelerating the reddening of buds and leaves, and also improves the enzymatic hydrolysis reaction of exogenous enzymes, converting them into a large amount of enzymatic hydrolysis products to optimize the quality of the yeast-infused black tea. Simultaneously, the outer cover can be opened for open dual-enzyme fermentation, allowing for the dissipation of humid and fermented gases, which is beneficial for subsequent drying and aroma enhancement.

[0012] To efficiently remove moisture from yeast-infused black tea and enhance its aroma, the hot air pre-drying and aroma-enhancing roller includes a cylinder body with an inlet at one end and an outlet at the other. A rotating drum is installed inside the cylinder, arranged at an angle. Tea leaves enter from one end of the rotating drum and exit from the other. A hot air pipe, angled towards the inlet, is installed at the outlet end of the hot air pre-drying and aroma-enhancing roller, blowing hot air towards the inlet. This hot air pipe is connected to a hot air blower. The hot air blower continuously blows low-temperature hot air (around 40°C) into the hot air pre-drying and aroma-enhancing roller for pre-drying, dissipating the "fermented odor" produced during the tea's fermentation process and promoting the volatilization of aromatic substances, thus enhancing the sweet floral aroma. This machine continuously rotates the drum, causing the tea leaves to tumble and be conveyed forward. This facilitates the dissipation of moisture from the tea leaves, increasing the drying speed. Under the action of hot air, a large amount of humid heat and "fermented odor" are released, enhancing the sweet floral aroma and reducing the moisture content of the tea leaves by 20-25%, completing the initial drying process. Then, the freeze-drying process of the freeze dryer is used to remove more than 95% of the moisture and freeze-solidify the activity and oxidation reaction of polyphenol oxidase, making it a high-quality yeast black tea with strong vitality and fermentation power.

[0013] To efficiently freeze-dry yeast black tea, the screen in the receiving frame is wavy. Support plates are installed on both sides of the tray, and floating plates are mounted on these plates. A set of support springs connects the floating plates to the support plates. A vibrator is also installed on the back of the floating plates. During freeze-drying, the vibrator is activated, causing the tea leaves to bounce within the receiving frame, thus expelling moisture and accelerating drying. The vacuum freeze dryer utilizes low-temperature vacuum drying technology, freezing the yeast black tea at a low temperature and then removing moisture under vacuum to achieve drying. Yeast black tea produced using this freeze-drying process retains the fermentation activity of polyphenol oxidase and possesses excellent qualities such as a glossy color, no overly roasted taste, red leaves, red liquor, and a sweet aroma.

[0014] The beneficial effects of this invention are as follows: The production line designed by this invention not only enables continuous and automated processing of yeast black tea, reducing production costs, but also maximizes the preservation of polyphenol oxidase activity in tea leaves, resulting in a high-quality yeast black tea with red leaves, red liquor, sweet aroma, and strong fermentation power.

[0015] The quantitative impurity removal feeding conveyor ensures the quantity of tea leaves for each withering and fermentation process, and removes impurities to prevent adverse effects on subsequent withering and fermentation, thereby improving tea quality. The withering and fermentation machine can perform segmented temperature-controlled withering and fermentation. Segmented withering effectively enhances, stabilizes, and weakens the activity of polyphenol oxidase, facilitating the release of grassy odors and the formation of aromatic substances, thus improving the withering quality of buds and leaves. The three-stage photothermal steam fermentation process stimulates, enhances, and boosts the fermentation kinetics of polyphenol oxidase, promoting the formation of large quantities of tea polyphenols, caffeine, amino acids, and other substances in the buds and leaves. It particularly strengthens the oxidation, polymerization, and condensation reactions of catechins, forming theaflavins, thearubigins, and theabrownins. Its fermentation quality is superior to conventional black tea fermentation processes, which is beneficial for producing high-quality yeast-fermented black tea.

[0016] The described kneading and de-clumping fermentation machine, through improvements to the kneading drum, utilizes wood and ceramic materials, which do not antagonize with metal materials. This facilitates efficient enzymatic hydrolysis of polyphenol oxidase and exogenous enzymes, accelerating the reddening of buds and leaves to achieve superior quality with red leaves, red liquor, and a sweet aroma. Simultaneously, enzyme addition, oxygenation, and temperature control can be achieved through the drum lid. While ensuring thorough kneading, it promotes oxidative hydrolysis of tea leaves, transforming them into abundant pectin, tea polysaccharides, theanine, and aromatic substances, thus optimizing the quality of black tea yeast. Furthermore, a de-clumping roller is used for dynamic de-clumping, ensuring thorough de-clumping and even distribution of tea leaves into the fermentation tank. The fermentation tank can be temperature- and humidity-controlled, and can operate in both closed and open fermentation modes, allowing for better control of fermentation quality.

[0017] This invention employs an integrated hot air drying and aroma-enhancing machine with vacuum freeze drying. First, the aroma-enhancing drum is used for initial drying to improve the aroma and flavor of black tea, while preserving the activity of polyphenol oxidase to the maximum extent. Then, the tea is freeze-dried in a vacuum freeze dryer, which puts the polyphenol oxidase into a dormant state without killing its activity. This makes it easier for the polyphenol oxidase to participate as yeast in the later fermentation of other plants.

[0018] The present invention will now be described in more detail with reference to the accompanying drawings and embodiments. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the production line of the present invention.

[0020] Figure 2 This is a front view of the quantitative impurity removal feeding conveyor in this invention.

[0021] Figure 3 This is a front view of the withering fermentation machine in this invention.

[0022] Figure 4 This is a side view of the spiked hot air leaf turner in this invention.

[0023] Figure 5 This is a side view of the ∩-shaped bushing in this invention.

[0024] Figure 6 This is a front view of the telescopic partition in this invention.

[0025] Figure 7 This is a front view of the kneading machine in this invention.

[0026] Figure 8 This is a front view of the disassembly roller in this invention.

[0027] Figure 9 This is a schematic diagram of the elongated material discharge port structure in this invention.

[0028] Figure 10 This is a front view of the fermentation tank in this invention.

[0029] Figure 11 This is a side view of the fermentation tank in this invention.

[0030] Figure 12 This is a front view of the hot air pre-drying and aroma-enhancing roller in this invention.

[0031] Figure 13 This is a front view of the vacuum freeze dryer in this invention.

[0032] Figure 14 This is a front view of the integrated hot air drying and aroma enhancement machine and vacuum freeze drying machine of the present invention.

[0033] Figure 15 This is a front view of the lifting frame in this invention.

[0034] Figure 16 This is a cross-sectional view of the feeder in this invention.

[0035] Figure 17 This is a top view of the material pushing platform in this invention. Detailed Implementation

[0036] Examples, such as Figures 1 to 17As shown, a continuous production line for preparing yeast black tea using bio-fermentation includes a quantitative impurity removal feeding conveyor 1, a withering fermentation machine 2, a rolling and de-clumping fermentation machine 3, and a hot air drying, aroma enhancement, and vacuum freeze-drying integrated machine 4, connected in sequence. This production line enables continuous processing of yeast black tea. Simultaneously, it allows for precise temperature control at each step of tea processing, thereby reducing the loss of polyphenol oxidase activity in the tea leaves. Freeze-drying completes the final drying and shaping of the tea leaves, preserving a high level of polyphenol oxidase activity. Therefore, the yeast black tea processed by this production line not only has a good taste but can also be used as yeast to ferment other plants together. The polyphenol oxidase in the tea promotes the fermentation of other plants, thus enabling its use in the production of compound black tea.

[0037] The specific structures and connection relationships of the various devices in this invention are as follows:

[0038] The quantitative impurity removal feeding conveyor 1 includes a feeding hopper 11, an impurity removal conveyor belt 12 disposed below the feeding hopper 11, a weighing device 13 disposed below the feeding hopper 11, and an impurity removal device 14 disposed on the impurity removal conveyor belt 12. Specifically, the feeding hopper 11 is a "trumpet-shaped" stainless steel structure, located at the front end of the impurity removal conveyor belt 12, so that fresh tea leaves are weighed in the feeding hopper 11 and laid onto the impurity removal conveyor belt 12. The weighing device 13 is an R546H type electronic sensor weigher, installed in the feeding hopper 11 for weighing, so as to achieve quantitative withering and improve withering quality. The impurity removal device 14 includes an electromagnetic roller 141 and an impurity suction hood 142 located above the electromagnetic roller 141, which is installed at the discharge end of the impurity removal conveyor belt 12, so as to absorb dust, fibers, hair, broken flower leaves, metal debris, etc., from the fresh tea leaves during the discharge process. The screen conveyor belt is an 8-10 mesh stainless steel screen conveyor belt, which is arranged at an upward inclination of 12-15 degrees. Its discharge end is connected to the feed trough 210 of the photothermal withering layer of the withering fermentation machine 2, so that the tea leaves can be screened to remove mud, sand, small insects, insect eggs, and debris during the conveying process, and the cleaned tea leaves can then undergo photothermal withering. The technical effect of the quantitative impurity removal feeding conveyor of this invention is as follows: by using electromagnetic rollers, impurity suction hoods, and inclined screen conveyor belts, dust, mud, small insects, insect eggs, fibers, hair, broken flower leaves, and metal debris carried in the fresh leaves can be removed, so that the cleaned tea leaves can be quantitatively fed into the photothermal withering layer of the withering fermentation machine for photothermal withering to produce yeast black tea, which helps to ensure product quality and safety.

[0039] The withering and fermentation machine 2 includes a tank 21 made of stainless steel. To ensure the continuous withering and fermentation process of making yeast black tea, the tank 21 has a two-layer structure: an upper heat withering layer 22 and a lower heat steam fermentation layer 23. The bottom of the heat withering layer 22 is equipped with a stainless steel mesh conveyor belt 24 that transports tea leaves from left to right. The bottom of the heat steam fermentation layer 23 is equipped with a reciprocating mesh conveyor belt 25. To ensure the tea leaves can smoothly enter the lower reciprocating mesh conveyor belt 25, an inlet / outlet chute 26 for the heat steam fermentation layer is located below the outlet end of the stainless steel mesh conveyor belt 24. One end of the reciprocating mesh conveyor belt 25 extends into the inlet / outlet chute 26 to receive tea leaves from the upper stainless steel mesh conveyor belt 24.

[0040] A feeding trough 210 is provided on the left side of the photothermal withering layer 22. The bottom of the stainless steel screen conveyor belt 24 is made of 20-mesh stainless steel screen. The stainless steel screen conveyor belt 24 is driven by a clockwise rotating belt pulley to move from left to right for photothermal withering. The withered tea leaves are then transported from the feeding trough 26 to the photothermal steam fermentation layer 23 for photothermal steam fermentation. In order to evenly spread the fresh tea leaves on the stainless steel screen conveyor belt 24 and to pierce the cell walls so that the photothermal heat can penetrate into the inner layer of the cells for withering, a stainless steel thorn-shaped leaf-equalizing roller 211 is provided in the feeding trough 210. The roller rotates clockwise to evenly distribute the leaves and break down the cell structure of the buds and leaves. Above the stainless steel screen conveyor belt 24, counter-rotating spiky hot air leaf turners 213 are installed at intervals. Each spiky hot air leaf turner 213 includes a hollow rotating roller 2131 and spiky claws 2132 mounted on the roller. One end of the rotating roller 2131 is connected to a hot air pipe 292 via a rotating joint (existing technology, not described in detail here). Air outlet holes 21311 are provided on the surface of the rotating roller 2131. Through its clockwise and counter-clockwise rotation, it can both turn and blow hot air to heat the tea leaves, and also pierce the cell walls to allow photothermal heat to penetrate into the inner cell layer for photothermal withering.

[0041] To improve the withering quality of yeast-treated black tea, two vertically movable partitions 27 are installed within the photothermal withering layer 22. These partitions 27 divide the photothermal withering layer 22 from left to right into three independent withering chambers: a high-temperature withering chamber 221, a medium-temperature withering chamber 222, and a low-temperature withering chamber 223, achieving segmented photothermal withering. To facilitate control of the vertical movement of the partitions 27, a crossbeam 214 is installed above the photothermal withering layer 22. A cylinder 215 is mounted on the crossbeam 214 to drive the partitions 27 vertically. When segmentation is required, the cylinder 215 moves the partitions 27 downwards, with their bottoms resting against the stainless steel mesh conveyor belt 24, thus dividing the photothermal withering layer 22 into independent withering chambers. When the tea leaves need to move to the right, the cylinder 215 moves the partitions 27 upwards, facilitating the removal of the tea leaves.

[0042] To facilitate temperature control in each withering chamber, each withering chamber is equipped with a U-shaped support frame 217. Infrared electric heating lamps 291 and hot air pipes 292 are mounted on the U-shaped support frame 217. These together form a temperature control device 29. By installing infrared electric heating lamps 291 and hot air pipes 292 with different wattages and inputting hot air at different temperatures, the temperature of each withering chamber is adjusted, allowing for photothermal withering of the fresh tea leaves on the stainless steel mesh conveyor belt 24. The fresh tea leaves on the stainless steel mesh conveyor belt 24 are sequentially withered through a series of chambers: a high-temperature withering chamber 221, a medium-temperature withering chamber 222, and a low-temperature withering chamber 223. First, they pass through the high-temperature withering chamber, where a temperature of approximately 40°C enhances the activity of polyphenol oxidase, causing the buds and leaves to lose water and wither, resulting in a reddish color change. After high-temperature withering, partition 27 moves upward to open, and the stainless steel screen conveyor belt 24 moves to the right, allowing the tea leaves to enter the medium-temperature withering chamber. Partition 27 then moves downward to close, and the medium temperature of approximately 35℃ stabilizes the activity of polyphenol oxidase, promoting the enzymatic transformation of starch, protein, cellulose, and other substances in the fresh tea leaves, resulting in a sweet floral aroma. After the medium-temperature withering process, the stainless steel screen conveyor belt moves to the right, and the tea leaves enter the low-temperature withering chamber. The low temperature of approximately 32℃ weakens the activity of polyphenol oxidase, preventing over-withering, excessive water loss, and leaf dryness. The beneficial effects of using segmented photothermal withering technology include: promoting the enzymatic transformation of starch, protein, cellulose, and other substances in fresh tea leaves, resulting in a sweet floral aroma and improved withering quality.

[0043] The feed inlet of the photothermal steam fermentation layer 23 is located below the feed trough 26. To ensure that the tea leaves in the photothermal withering layer 22 fall smoothly onto the reciprocating screen conveyor belt 25 of the photothermal steam fermentation layer 23, a guide plate 261 is provided in the feed trough 26 so that the tea leaves fall directly into the feed inlet below. In order to evenly spread the tea buds and leaves on the reciprocating screen conveyor belt 25 and to break the cell walls, a spiky leaf-equalizing roller 211 and a steam nozzle 212 are provided in the feed trough 26. The spiky leaf-equalizing roller 211 rotates clockwise, and the steam nozzle 212 sprays 40°C steam. This can both heat and humidify the tea leaves after photothermal withering for biological fermentation, and the combined action of the steam force and the spiky leaf-equalizing roller 211 can further break the cell structure of the tea buds and leaves so that the photothermal heat can penetrate into the inner cell layer to stimulate the activity of polyphenol oxidase for biological fermentation. In addition, the reciprocating screen conveyor belt 25 is also equipped with a thorny hot air leaf turner 213 that rotates in both directions. Through its clockwise and counterclockwise rotation, it can both turn the tea leaves and blow hot air to heat them, and it can also pierce the cell wall so that light and heat can penetrate into the inner layer of the cell for photothermal steam bio-fermentation.

[0044] To improve the fermentation quality of yeast-fermented black tea, two telescopic partitions 28 are installed inside the photothermal steam fermentation layer 23. When opened, the telescopic partitions 28 divide the photothermal steam fermentation layer 23 from right to left into three independent fermentation chambers: a low-temperature fermentation chamber 231, a medium-temperature fermentation chamber 232, and a high-temperature fermentation chamber 233. The telescopic partitions 28 and partitions 27 are substantially aligned vertically. When the telescopic partitions 28 are open, their upper ends rest against the underside of the stainless steel screen conveyor belt 24, and their lower ends press against the reciprocating screen conveyor belt 25. This structure allows the light and heat from the lower low-temperature fermentation chamber 231 to reach the lower part of the low-temperature withering chamber 223 through the stainless steel screen conveyor belt 24, thus providing a photothermal effect on the tea leaves in the lower part of the low-temperature withering chamber 223. Similarly, the light and heat from the medium-temperature fermentation chamber 232 can reach the lower part of the medium-temperature withering chamber 222 through the stainless steel screen conveyor belt 24, thus providing a photothermal effect on the tea leaves in the lower part of the medium-temperature withering chamber 222. The light and heat from the high-temperature fermentation chamber 233 can reach the lower part of the high-temperature withering chamber 221 through the stainless steel screen conveyor belt 24, thus providing a photothermal effect on the tea leaves in the lower part of the high-temperature withering chamber 221, overcoming the technical obstacle that the fresh tea leaves at the bottom of the photothermal withering trough cannot receive light and heat.

[0045] The specific installation structure of the telescopic partition 28 is as follows: two transverse rotating shafts 216 are rotatably installed above the photothermal steam fermentation layer 23. The transverse rotating shafts 216 are driven by a motor. Rotating gears 2161 are provided at both ends of the transverse rotating shafts 216. The telescopic partition 28 includes an upper partition 281 and a lower partition 282. Both the upper partition 281 and the lower partition 282 are provided with racks 283 that cooperate with the rotating gears 2161. When the transverse rotating shafts 216 rotate, the upper partition 281 and the lower partition 282 can be opened and closed under the cooperation of the rotating gears 2161 and the racks 283.

[0046] To facilitate temperature control in each fermentation chamber, a U-shaped frame 217 is installed in each chamber. Infrared electric heating lamps 291 and hot air pipes 292 are mounted on the U-shaped frame 217. These together form a temperature control device 29. By installing infrared electric heating lamps 291 and hot air pipes 292 with different wattages and inputting hot air at different temperatures, the temperature of each fermentation chamber is adjusted, allowing for photothermal steam bio-fermentation of the fresh tea leaves on the reciprocating screen conveyor belt 25. The withered tea leaves move along the reciprocating conveyor belt 25, undergoing fermentation in a progressive manner: "low-temperature fermentation chamber → medium-temperature fermentation chamber → high-temperature fermentation." First, in the low-temperature fermentation chamber 231, the activity of polyphenol oxidase is activated by photothermal stimulation at approximately 31°C, initiating low-temperature fermentation. After low-temperature fermentation, the reciprocating screen conveyor belt 25 moves to the left, feeding the tea leaves into the medium-temperature fermentation chamber 232, where the activity of polyphenol oxidase is enhanced by photothermal stimulation at approximately 35°C, initiating medium-temperature fermentation. After the mesophilic fermentation is completed, the reciprocating screen conveyor belt 25 continues to move to the left, feeding the tea leaves into the high-temperature fermentation chamber 233. High-temperature steam at approximately 40°C enhances the bio-fermentation activity of polyphenol oxidase, resulting in a large amount of fermentation hydrolysis products. The beneficial effects of using a three-stage photothermal steam fermentation process (low temperature, mesophilic temperature, and high temperature) include: enhancing the fermentation activity of polyphenol oxidase, generating a large amount of enzymatic hydrolysis products, and optimizing the quality of yeast-infused black tea.

[0047] To control the temperature and humidity of each withering chamber and fermentation chamber, a control system 220 is also provided, and a temperature sensor 218 and a humidity sensor 219 are installed in each withering chamber and fermentation chamber. The control system 220 receives the signals from the temperature sensor 218 and the humidity sensor 219, and controls the air inlet temperature and air volume of the hot air duct 292 to adjust the temperature and humidity in each withering chamber and fermentation chamber.

[0048] The bottom of the feed trough 26 is connected to an elevator 100, which transports the fermented tea leaves to the kneading drum 311 of the kneading machine 31, where the tea leaves are kneaded. The kneading and de-clumping fermentation machine 3 includes a kneading machine 31 and a de-clumping roller 33 connected to the discharge end of the kneading machine 31. The discharge end of the de-clumping roller 33 is connected to the fermentation tank 32.

[0049] The kneading machine 31 includes a kneading drum 311, a kneading disc 312, and a lid 313. The kneading disc 312 is provided with an openable and closable tea outlet. The matching structure of the kneading drum 311, the kneading disc 312, and the lid 313 is the same as that of existing kneading machines. The lid 313 is an adjustable pressure lid, all of which are existing technologies and will not be described in detail here. To adapt to the processing of yeast black tea, the present invention makes the following improvements to the kneading machine 31: In order to avoid adverse antagonistic reactions between the added exogenous enzymes and the metal materials, and to overcome the technical obstacles of coarse old tea buds and leaves with high cellulose content and hard leaves that are difficult to knead into strips, the kneading drum 311 and the lid 313 are made of pine wood. The kneading disc 312 and the kneading ribs above it are made of nano-ceramic material. When the tea leaves are rotated and kneaded in the nano-ceramic kneading disc, the inclined, hard and smooth ceramic ribs can be used to break the cell walls of the tea buds and leaves, allowing the tea juice to overflow so that it can be kneaded into strips, while also reducing broken tea leaves. To prevent excessively high tea temperature during pressure kneading from reducing polyphenol oxidase activity, a temperature sensor 315 is installed on the lid 313, extending deep into the kneading drum 311. A hot and cold air duct 316 is also provided to regulate the temperature inside the kneading drum 311. The other end of the hot and cold air duct 316 is connected to a hot and cold air blower, which adjusts the temperature of the hot and cold air to ensure that the tea leaves inside the kneading drum remain within a certain temperature range during kneading, thus preventing the loss of polyphenol oxidase activity due to high temperatures. Furthermore, an oxygen supply pipe 317 is provided to deliver oxygen into the kneading drum 311, and an atomizing enzyme addition nozzle 318 is provided for adding exogenous enzymes. During the rolling process, exogenous biological enzymes can be added using the atomizing enzyme nozzle 318 for enzymatic rolling, oxygen can be introduced using the oxygen supply pipe 317 for oxygenated rolling, and the rolling temperature can be adjusted using the hot and cold air pipes. This promotes the efficient oxidation reaction of polyphenol oxidase in the tea leaves, accelerates the reddening of the rolling buds and leaves, and also promotes the efficient enzymatic hydrolysis reaction of exogenous biological enzymes to hydrolyze substances such as cellulose, softening the leaf texture to facilitate the rolling of coarse and old tea buds and leaves into strips, and transforming them into a large amount of pectin, tea polysaccharides, theanine, and aromatic substances to optimize the quality of yeast black tea.

[0050] After kneading, the tea leaves enter the feed inlet of the de-clumping roller 33 below through the central discharge port of the kneading disc 312. To quickly break up tea clumps, the de-clumping roller 33 includes an inclined roller body 331, which is rotatably mounted on the frame 335 and driven by a drive motor. Inside the roller body 331 is a screening cage 332 that rotates with the roller body 331. One end of the screening cage 332 has a tea inlet, and the other end is closed. The roller body 331 has an outlet at the opposite end of the tea inlet. Inside the screening cage 332 are de-clumping rollers 333 that move relative to the screening cage 332. Each de-clumping roller 333 is equipped with a dispersing rod 334. The de-clumping rollers 333 can be directly fixed to the frame 335 by a support rod. When the screening cage 332 rotates, the de-clumping rollers 333 remain stationary, thus achieving relative rotation. The surface of the screening roller is also provided with a set of discharge holes 3321. The broken tea leaves fall into the roller body 331 through the discharge holes 3321. Under the combined action of the tilt angle and rotational force, the broken tea leaves move towards the outlet for output. The discharge holes 3321 are elongated structures adapted to the tea leaves, which facilitates the falling of the rolled tea leaves and prevents the tea clumps from falling. The tea clumps are then continuously broken up by the de-clumping roller 333 and fall through the discharge holes 3321, thus ensuring thorough de-clumping.

[0051] The discharge port of the disintegrating roller 33 is located above the feed end of the fermentation tank 32. A screen conveyor belt 34 is installed inside the fermentation tank 32, and a leaf-spreading roller 322 is installed at the feed end of the fermentation tank 32. Tea leaves falling from the discharge port of the disintegrating roller 33 land on the screen conveyor belt 34. Through the slow forward movement of the screen conveyor belt 34 and the action of the leaf-spreading roller 322, the tea leaves are evenly spread on the screen conveyor belt 34 for fermentation. To enable dual-enzyme biological fermentation without antagonistic reactions, the fermentation tank 32 is designed with a double-layer structure. Its inner wall is made of cedar wood, and its outer wall is an insulation layer of nano-quartz material, thus achieving metal-free disintegration and dual-enzyme biological fermentation. To improve fermentation efficiency and quality, three U-shaped supports 323 are spaced apart on the fermentation tank 32. Each U-shaped support 323 is equipped with a quartz infrared electric heating lamp 39, a hot air pipe 310, and a misting humidification nozzle 320. This facilitates temperature regulation during fermentation via light and heat, and humidity regulation via the misting humidification nozzle 320. The fermentation process involves photothermal and steam dual-enzyme fermentation of the buds and leaves after enzyme addition and kneading. The technical effects of using the photothermal and steam heating devices are as follows: Infrared light is emitted from the infrared electric heating lamps into the buds and leaves, stimulating the activity of polyphenol oxidase and exogenous enzymes for dual-enzyme biological fermentation. Hot air is blown into the tank to enhance the enzymatic fermentation dynamics, resulting in a large amount of fermentation enzymatic hydrolysis products. Steam nozzles provide heating and humidification, stabilizing the enzymatic fermentation dynamics of polyphenol oxidase and exogenous enzymes and preventing the buds and leaves from drying out, which would affect fermentation quality.

[0052] The discharge end of the fermentation tank 32 is connected to an elevator 100, and the discharge end of the elevator 100 is connected to the feed end of the hot air pre-drying and aroma-enhancing roller 41. The integrated hot air drying and aroma-enhancing and vacuum freeze-drying machine 4 includes a hot air pre-drying and aroma-enhancing roller 41, a receiving conveyor belt 42 connected to the discharge port of the hot air pre-drying and aroma-enhancing roller 41, a set of screen receiving frames 43 is provided on the receiving conveyor belt 42, a receiving frame elevator 44 is connected to the discharge end of the receiving conveyor belt 42, and a vacuum freeze dryer 45 is connected to the receiving frame elevator 44. The vacuum freeze dryer 45 is provided with a drawer 451 for placing the screen receiving frames 43. This invention first uses a hot air preheating and aroma-enhancing roller 41 to dry and enhance the aroma of tea leaves. Then, the hot-air dried and aroma-enhanced tea leaves are transported to a vacuum freeze dryer 45 via a receiving conveyor belt 42 and a receiving frame elevator 44 for freeze drying. This invention is not only highly automated, but also uses a structure that combines hot air drying and freeze drying, which can both improve the aroma of tea leaves and maintain the activity of polyphenol oxidase in yeast black tea.

[0053] Specifically, the hot air pre-drying and aroma-enhancing drum 41 includes a cylinder 411 inclinedly arranged on a frame. One end of the cylinder 411 has a feed inlet, and the other end has a discharge outlet. A rotating drum 412 is installed inside the cylinder 411. Tea leaves enter the rotating drum 412 through the feed inlet. The rotation of the rotating drum 412 causes the tea leaves to tumble and be slowly conveyed forward within the drum. To achieve dynamic drying, a hot air pipe 413 inclined towards the feed inlet is installed at the discharge end of the hot air pre-drying and aroma-enhancing drum 41. A hot air blower 414 is connected to the hot air pipe 413. The hot air blower 414 continuously delivers hot air at approximately 40°C into the cylinder 411 through the hot air pipe 413. Combined with the rotation of the rotating drum 412, the tea leaves are dynamically dried using hot air.

[0054] To automatically feed the pre-dried and aroma-enhanced tea leaves into the vacuum freeze dryer 45 for vacuum freeze drying, a receiving conveyor belt 42 is installed below the discharge port of the hot air pre-dried and aroma-enhancing drum 41. The screen receiving frame 43 inside the vacuum freeze dryer 45 is manually placed onto the receiving conveyor belt 42, and the running speed of the receiving conveyor belt 42 is controlled to ensure that the tea leaves falling from the hot air pre-dried and aroma-enhancing drum 41 are evenly spread in the screen receiving frame 43. Then, the receiving conveyor belt 42 sends the screen receiving frame 43 containing the tea leaves to the pushing platform 442 of the receiving frame elevator 44. After the height of the screen receiving frame 43 is adjusted by the receiving frame elevator 44, the screen receiving frame 43 is then sent into the corresponding shelf 451.

[0055] To facilitate the addition of vitamin C to inhibit the oxidation of polyphenol oxidase, the feeding platform 442 is also equipped with an atomizing enzyme adder 4422 for adding vitamin C. When the tea leaves pass through the feeding platform 442, a certain amount of vitamin C is sprayed into the tea leaves through the atomizing enzyme adder 4422 for anti-oxidation.

[0056] The receiving frame elevator 44 includes an elevator frame 441, a pushing platform 442 mounted on the elevator frame 441, and a lifting screw 443 that drives the pushing platform 442 up and down. During material receiving, the lifting screw 443 first drives the pushing platform 442 to move, ensuring the pushing platform 442 is flush with or slightly lower than the receiving conveyor belt 42, allowing the front end of the screen receiving frame 43 to smoothly transition onto the pushing platform 442. To facilitate pulling the screen receiving frame 43 forward on the pushing platform 442, a transfer conveyor chain 444 is also provided below the pushing platform 442. A set of pushing blocks 445 are mounted on the transfer conveyor chain 444, with the distance between adjacent pushing blocks 445 matching the length of the screen receiving frame 43. The pushing platform 442 is provided with a pushing block clearance groove 4421, and the pushing block 445 extends out of the pushing block clearance groove 4421 and beyond the upper surface of the pushing platform 442. When one end of the screen receiving frame 43 enters the pushing platform 442, the transfer conveyor chain 444 rotates. As one of the pushing blocks 445 on the transfer conveyor chain 444 moves forward, it abuts against the frame edge of the screen receiving frame 43 and pulls the entire screen receiving frame 43 forward. When the entire screen receiving frame 43 has entered the pushing platform 442, the lifting screw 443 drives the pushing platform 442 to move, so that the screen receiving frame 43 reaches the height position of the corresponding shelf 451 of the vacuum freeze dryer 45. Then the transfer conveyor chain 444 continues to rotate, so that the subsequent pushing block 445 pushes the screen receiving frame 43 into the shelf 451.

[0057] To ensure the rear end of the screen receiving frame 43 can fully enter the drawer 451, two pushing cylinders 446 are provided at the end of the pushing platform 442 and on both sides of the transfer conveyor chain 444. Each pushing cylinder 446 has a feeding element 447 at its movable end, and a retractable movable stop 448 is provided on the feeding element 447. A push-out spring 449 is provided between the movable stop 448 and the feeding element 447. The upper surface of the movable stop 448 is an arc surface with a lower rear end and a higher front end. When the movable stop 448 is not under force, it is pushed out beyond the pushing platform 442 by the spring force, allowing for material pushing. As the screen receiving frame 43 moves forward from the rear end, it presses down the movable stop 448 along the arc surface of its upper surface. Under the pressure, the movable stop 448 controls the spring force to move downward and become flush with the pushing platform 442. The screen receiving frame 43 can then pass smoothly through the movable stop 448. When the screen receiving frame 43 moves forward to the front end of the movable stop 448, the movable stop 448 is pushed out without force. At this time, the pushing cylinder 446 works, which pushes the screen receiving frame 43 forward until it is completely inside the drawer 451, completing the placement of the screen receiving frame 43. Then the pushing cylinder 446 returns to its initial position, and at the same time, the pushing platform 442 returns to the docking position height of the receiving conveyor belt 42, ready for the transport of the next screen receiving frame 43.

[0058] The vacuum freeze dryer 45 has a box-type structure and is equipped with multiple drawers 451. It also features an automatic sensor door 452 for convenient automatic feeding. To allow the tea leaves to move within the screen receiving frame 43 during freeze-drying, accelerating the process, the screen of the screen receiving frame 43 is preferably wavy. Support plates 4511 are located on both sides of the drawers 451, with floating plates 4512 mounted on them. The screen receiving frame 43 rests on the floating plates 4512. A set of support springs 4513 connects the floating plates 4512 and the support plates 4511. A vibrator 46 is located on the back of the floating plates 4512, causing the floating plates 4512 and the screen receiving frames 43 on them to vibrate, thus making the tea leaves move. The basic principle of the vacuum freeze dryer 45 is the same as that of existing vacuum freeze dryers, and it has a refrigeration system, a vacuum system, a circulation system, a control system, and a hydraulic system. Its freeze-drying process is as follows: pretreatment → pre-freezing (quick freezing) → rapid cooling by a water trap → vacuuming of the chamber → drying and sublimation → freeze-drying and unloading. Using a vacuum freeze dryer to dry yeast black tea yields beneficial results: it not only avoids the tendency of conventional high-temperature drying methods to cause leaf dryness and a strong burnt taste, but also maintains high activity of polyphenol oxidase, resulting in yeast black tea with strong fermentation potential.

[0059] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution; or the direct application of the inventive concept and technical solution to other situations without modification, are all within the protection scope of the present invention.

Claims

1. A continuous production line for preparing yeast black tea using bio-fermentation, characterized in that: It includes a quantitative impurity removal and feeding conveyor (1), a withering fermentation machine (2), a kneading and de-blocking fermentation machine (3), and a hot air drying and aroma enhancement and vacuum freeze drying integrated machine (4) connected in sequence. The withering fermentation machine (2) includes a tank (21), the upper layer of which is a photothermal withering layer (22) and the lower layer is a photothermal steam fermentation layer (23). A stainless steel screen conveyor belt (24) is provided at the bottom of the photothermal withering layer (22), and a reciprocating moving screen conveyor belt (25) is provided at the bottom of the photothermal steam fermentation layer (23). An inlet / outlet chute (26) is provided below the discharge end of the stainless steel screen conveyor belt (24), and one end of the reciprocating moving screen conveyor belt (25) extends into the inlet / outlet chute (26) to receive feed from the stainless steel screen. Tea leaves on the conveyor belt (24); the photothermal withering layer (22) is provided with two vertically movable partitions (27), which divide the photothermal withering layer (22) into independent high-temperature withering chamber (221), medium-temperature withering chamber (222) and low-temperature withering chamber (223); the photothermal steam fermentation layer (23) is also provided with two telescopic partitions (28), which divide the photothermal steam fermentation layer (23) into independent low-temperature fermentation chamber (231), medium-temperature fermentation chamber (232) and high-temperature fermentation chamber (233); The integrated hot air drying and aroma enhancement and vacuum freeze drying machine (4) includes a hot air pre-drying and aroma enhancement drum (41) and a receiving conveyor belt (42) connected to the discharge port of the hot air pre-drying and aroma enhancement drum (41). A set of screen receiving frames (43) is provided on the receiving conveyor belt (42). A receiving frame elevator (44) is connected to the discharge end of the receiving conveyor belt (42). A vacuum freeze dryer (45) is connected to the receiving frame elevator (44). A shelf (451) for placing the screen receiving frames (43) is provided inside the vacuum freeze dryer (45).

2. The continuous production line for preparing yeast black tea using bio-fermentation according to claim 1, characterized in that: The kneading and de-caking fermentation machine (3) includes a kneading machine (31), a de-caking roller (33) connected to the discharge end of the kneading machine (31), and a fermentation tank (32) connected to the de-caking roller (33); a screen conveyor belt (34) is provided inside the fermentation tank (32); the de-caking roller (33) includes an inclined roller body (331), and a screening roller (332) is provided inside the roller body (331) that rotates together with the roller body (331). One end of the drum body (331) is provided with a tea inlet, and the other end is a closed structure. One end of the drum body (331) is provided with a discharge outlet. The screening drum (332) is provided with a disintegrating roller (333) that moves relative to the screening drum (332). The disintegrating roller (333) is provided with a dispersing rod (334). The surface of the screening drum (332) is also provided with a set of dropping holes (3321). The disintegrated tea leaves fall into the drum body (331) from the dropping holes (3321).

3. The continuous production line for preparing yeast black tea using bio-fermentation according to claim 1, characterized in that: The feed end of the photothermal withering layer (22) is provided with a feed trough (210), and a thorny leaf-equalizing roller (211) for evenly distributing leaves and piercing the surface of the tea leaves is provided in the feed trough (210); a thorny leaf-equalizing roller (211) is also provided in the feed trough (26), and a steam nozzle (212) for humidification is also provided; a temperature control device (29) is provided in the high temperature withering chamber (221), the medium temperature withering chamber (222), the low temperature withering chamber (223), the low temperature fermentation chamber (231), the medium temperature fermentation chamber (232) and the high temperature fermentation chamber (233).

4. The continuous production line for preparing yeast black tea using bio-fermentation according to claim 1, characterized in that: A crossbeam (214) is provided above the photothermal withering layer (22), and a cylinder (215) is provided on the crossbeam (214) to drive the partition (27) to move up and down; two transverse rotating shafts (216) are provided above the photothermal steam fermentation layer (23), and rotating gears (2161) are provided at both ends of the transverse rotating shafts (216); the telescopic partition (28) includes an upper partition (281) and a lower partition (282), and a rack (283) that cooperates with the rotating gear (2161) is provided on both the upper partition (281) and the lower partition (282).

5. The continuous production line for preparing yeast black tea using bio-fermentation according to claim 2, characterized in that: The kneading machine (31) includes a kneading drum (311), a kneading disc (312), and a drum cover (313); the drum cover (313) is provided with a temperature sensor (35) that extends into the kneading drum (311), and is also provided with a hot and cold air pipe (36) for adjusting the temperature inside the kneading drum (311); the drum cover (313) is also provided with an oxygen supply pipe (37) for supplying oxygen to the kneading drum (311) and an atomizing enzyme nozzle (38).

6. The continuous production line for preparing yeast black tea using bio-fermentation according to claim 2, characterized in that: The fermentation tank (32) is provided with an openable outer cover (321); the fermentation tank (32) is provided with a set of quartz infrared electric heating lamps (39), hot air pipes (310) and atomizing humidifying nozzles (320).

7. The continuous production line for preparing yeast black tea using bio-fermentation according to claim 1, characterized in that: The hot air pre-drying aroma-enhancing roller (41) includes a cylinder (411), one end of which is provided with a feed inlet and the other end with a discharge outlet. A rotating drum (412) is provided inside the cylinder (411), and the rotating drum (412) is arranged at an angle. The tea leaves enter from one end of the rotating drum (412) and exit from the other end. The discharge end of the hot air pre-drying aroma-enhancing roller (41) is provided with a hot air pipe (413) that blows hot air at an angle toward the feed inlet. A hot air blower (414) is connected to the hot air pipe (413).

8. The continuous production line for preparing yeast black tea using bio-fermentation according to claim 1, characterized in that: The receiving frame elevator (44) includes an elevator frame (441), a pushing platform (442) set on the elevator frame (441), a lifting screw (443) that drives the pushing platform (442) to move up and down, a transfer conveyor chain (444) is also set on the pushing platform (442), and a set of pushing blocks (445) is set on the transfer conveyor chain (444), the distance between two adjacent pushing blocks (445) is adapted to the length of the screen receiving frame (43); At the end of the pushing platform (442) and on both sides of the transfer conveyor chain (444), there are two pushing cylinders (446). The moving end of the pushing cylinder (446) is provided with a feeder (447). The feeder (447) is provided with a retractable movable stop (448). The upper surface of the movable stop (448) is an arc surface with a lower rear end and a higher front end.

9. The continuous production line for preparing yeast black tea using bio-fermentation according to claim 8, characterized in that: The feeding platform (442) is also equipped with an atomizing enzyme adder (449) for adding vitamin C.

10. The continuous production line for preparing yeast black tea using bio-fermentation according to claim 8, characterized in that: The drawer (451) is provided with support plates (4511) on both sides, and a floating plate (4512) is provided on the support plate (4511). A set of support springs (4513) is provided between the floating plate (4512) and the support plate (4511). A vibrator (46) is also provided on the back of the floating plate (4512).

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