Preparation method of small-pot Baihao silver needle tea

Abstract

The invention discloses a small-pot Baihao silver needle tea preparation method which comprises the working procedures of raw material picking, xylan enzymolysis tedding, photo-thermal withering, cold air cooling, bromelain enzymolysis tea nourishing, temperature-controlled dynamic tea nourishing, impurity removal through a screening impurity removal machine, dual-heat drying and the like, and therefore the Baihao silver needle tea is prepared. By adopting the method disclosed by the invention, the processing efficiency of the Baihao silver needle tea can be improved, meanwhile, the processing quality of the Baihao silver needle tea can be improved, and the method can be widely applied to the processing field of the Baihao silver needle tea.

Description

Technical Field

[0001] This invention relates to the field of tea processing technology, and in particular to a method for preparing small-can Baihao Yinzhen tea. Background Technology

[0002] The traditional production method of Baihao Yinzhen tea is as follows: 1. Picking: Pick the plump and heavy single buds that grow in early spring on the tea tree, remove the fish-leaf scales and broken buds and leaves, and only take the whole white down. 2. Withering: (a) Natural withering: Spread the fresh tea buds thinly on a water sieve or withering sieve and place them in the gentle sunlight for sun withering. (b) Indoor heated withering: Spread the fresh tea buds thinly on a water sieve and place them in a heated withering chamber for heated withering. (c) Combined withering: Combine outdoor sun withering with indoor natural or heated withering. (d) Mechanical withering: Use withering troughs for heated withering. 3. Nourishing the tea: Spread the withered leaves evenly on a cloth or bamboo mat and let them nourish the tea naturally for 5-7 days. 4. Drying: (a) Sun drying: Dry the tea outdoors using direct sunlight. (b) Basket drying: Dry the tea in a charcoal-fired basket in a drying room. (c) Mechanical drying: Dry the tea using a tea drying machine. This indicates that the traditional method of producing Baihao Yinzhen tea suffers from numerous problems, including complex procedures, rudimentary equipment, manual handling, low efficiency, susceptibility to weather conditions, a bland taste due to lack of kneading, and difficulty in quality control. Therefore, it is necessary to develop a new method for preparing Baihao Yinzhen tea to overcome some of the technical shortcomings of the traditional process. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing small-can Baihao Yinzhen tea, which solves the problems of complicated procedures, low efficiency, and difficulty in quality control in existing Baihao Yinzhen tea processing methods.

[0004] The technical solution adopted by this invention to solve its technical problem is: a method for preparing small-can Baihao Yinzhen tea, the process flow is as follows: raw material picking → xylan enzymatic hydrolysis and spreading → light and heat withering → cold air drying → bromelain enzymatic hydrolysis for tea nourishment → temperature-controlled dynamic tea nourishment → sieving and impurity removal by a sieve → dual-heat drying → Baihao Yinzhen tea.

[0005] The specific steps for preparing the small-canned Baihao Yinzhen tea are as follows: 1) Raw material picking: Pick plump and heavy single buds, mainly of the Fuding Dahao tea variety, remove fish-leaf scales and broken buds and leaves, and only take whole white hairs.

[0006] 2) Adding xylanase during withering: The harvested tea leaves are fed into a windmill-type withering machine, and xylanase is added to the tea leaves for dynamic withering via rotation. The ratio of xylanase added to the weight of the withered tea leaves is set to 0.1-0.3%, and a solution with a concentration of 55-65% and a pH of 5.3-5.5 is prepared. The solution is added to the withered tea leaves in two stages through a rotary atomizing enzyme applicator and a trumpet-shaped atomizing enzyme applicator. The windmill rotation speed is set to 12-16 r / min, and the leaves are naturally withered for 1-2 hours. The blowing force of the rotating windmill promotes the thorough mixing of the added xylanase with the tea leaves to carry out the enzymatic reaction. The xylanase added in this process is a food-grade biological enzyme preparation, also known as endogenous 1,4-β-xylanase. It is a light brown powder with an effective substance content of 99%, an enzyme activity of 200,000 u / g, and an enzyme activity retention rate of 99%. Its main enzymatic function is to break down the structure of plant cell walls, promote the release of effective substances, decompose non-starch polysaccharides (NSPS) into xylooligosaccharides, and prevent the formation of non-carbohydrate turbidity. The technical effects of using the withering process with added xylanase are as follows: This enzyme decomposes the cell walls of tea leaves, causing their contents to overflow, solving the problem that Baihao Yinzhen tea, due to its low cell breakage rate from not being rolled, has difficulty in releasing its tea polyphenols, caffeine, amino acids, and tea polysaccharides, resulting in a weak taste and poor brewing endurance. At the same time, it also decomposes the non-starch polysaccharides (NSPS) in the tea leaves into xylooligosaccharides with a lower degree of polymerization, which not only adds a fresh, sweet, and mellow taste to the tea soup but also improves its clarity.

[0007] The windmill-type tea-spreading machine includes a frame, a reversible tea-spreading windmill mounted on the frame, a tea inlet hopper located above one side of the windmill, and a receiving device located below the other side. A set of tea-spreading mesh boxes are evenly arranged around the circumference of the windmill, each mesh box having a cover. Both the mesh boxes and covers are made of 18-20 mesh stainless steel. To enable the windmill to rotate clockwise and counterclockwise, its rotating shaft is connected to a reversible frequency-controlled motor via a rotating gear. The control system programmatically controls the reversible frequency-controlled motor, which drives the rotating shaft, thereby causing the windmill to perform reversible tea-spreading and to rotate at different speeds. A 360-degree rotating atomizing enzyme dispenser is installed inside the tea inlet hopper to spray xylanase atomized liquid evenly onto the tea leaves in the hopper. Above the tea-spreading fan on the other side of the tea-feeding basket, there is a funnel-shaped atomizing enzyme adder. This allows for a second downward spraying of xylanase atomized liquid onto the tea leaves in the lower tea-spreading mesh box 15. The rotating airflow generated during the forward and reverse rotation of the tea-spreading fan promotes the added xylanase liquid to penetrate into the inner layer of the tea leaves for enzymatic hydrolysis.

[0008] The technical effects of using a windmill-type foraging machine for two-stage enzyme-added foraging process are as follows: A 360-degree rotating atomizing enzyme applicator is arranged in the feed hopper of the foraging windmill, and a trumpet-mouth atomizing enzyme applicator is arranged above the foraging windmill. This allows the added xylanase solution to be evenly added to the foraged tea leaves in two stages. By rotating the foraging windmill in both directions, dynamic foraging and enzymatic reaction can be carried out, which can shorten the foraging time and improve the efficiency of enzymatic reaction and foraging. In particular, the enzymatic reaction of xylanase can increase the cell breakage rate of buds and hairs, allowing the contained tea polyphenols, amino acids, caffeine, tea polysaccharides and other compounds to overflow. This not only solves the problem of the weak taste and poor brewing endurance of traditionally processed Baihao Yinzhen tea, but also improves the fresh, sweet and mellow taste and clarity of the tea soup, thus enhancing the quality.

[0009] 3) Photothermal withering: After the tea leaves have been spread out, they are fed into the upper photothermal withering layer of the withering, drying, and tea-nurturing integrated machine for photothermal withering. The settings are: the leaf thickness is 10-15 cm, the turning claw turns the leaves for 1.5-2 minutes every 30 minutes, and the photothermal withering time is 3-5 hours. On sunny days, the withering, drying, and tea-nurturing machine is placed outdoors, and the red light-changing net on top is turned on to switch to red light for sunlight withering. On cloudy or rainy days, the withering, drying, and tea-nurturing machine is placed indoors to perform red and orange simulated light withering of the buds and leaves. Roll up the red light-changing net, turn on the quartz tube infrared heating lamp, first use the red light-changing cover to convert the infrared light into red simulated diffused light with a wavelength of 680-740nm, wither for 3-4 hours, then use the orange light-changing cover to convert the infrared light into orange simulated diffused light with a wavelength of 590-625nm, wither for 2-3 hours; and use the opening and closing of the cold air pipe and hot air pipe to control the withering temperature at 25-38°C, so that the moisture loss rate of the tea leaves is controlled between 12-14%; the beneficial effects of using photothermal withering technology are: on sunny days, the red diffused light converted by the light-changing net can wither the tea leaves, which can avoid the direct sunlight scorching the buds and leaves, and can also use the red diffused light to penetrate into the tea cells whose cell walls are decomposed by xylanase, stimulate the activity of the polyphenol oxidase contained therein, so that it produces oxidation, polymerization and degradation reactions, transforming into a large number of tea polysaccharides, amino acids, theaflavins and aromatic substances, thus forming the unique aroma and taste of Baihao Silver Needle. On cloudy or rainy days and at night, using a small infrared lamp and a light-changing cover, the infrared light is first changed to simulated red diffused light to efficiently wither the tea leaves, and then changed to orange simulated diffused light to stabilize the activity of polyphenol oxidase, further improving the efficiency of photothermal withering. At the same time, it can overcome the technical obstacle that photothermal withering cannot be carried out on cloudy or rainy days and at night, and can realize the production of Baihao Yinzhen tea around the clock.

[0010] 4) Cold air drying: The tea leaves after light and heat withering are fed into the second layer of cold air drying for cold air drying. The settings are: the thickness of the leaves is 7-9 cm, the drying time is 2-3 hours, the drying temperature is 20-25°C, and the leaves are turned over every 35 minutes for 1.5-2 minutes each time, so that the dried tea leaves lose 3-5% of their moisture again. Through the effect of cold air drying, the grassy smell, humid heat and moisture generated during light and heat withering are dissipated, making the leaves soft and the floral aroma initially appearing.

[0011] 5) Bromelain Enzymatic Hydrolysis for Tea Nourishment: After cold air drying, the tea leaves are fed into the third layer for enzymatic hydrolysis. The bromelain addition ratio is 0.1-0.3% (by weight of tea leaves), diluted to a 75% solution, and sprayed into the tea leaves using a centrifugal atomizer. The settings are: a frosted ceramic leaf-spreading roller speed of 16-18 r / min, a leaf thickness of 35-40 cm, a hydrolysis temperature of 38-42°C, a hydrolysis reaction time of 5-6 hours, and leaf turning every 40 minutes for 1-1.5 minutes to allow the tea leaves to lose 2-3% more moisture. The added bromelain is a food-grade natural plant enzyme preparation, extracted from the stems, leaves, and peel of pineapple fruits, and obtained through refining, purification, concentration, enzyme solidification, and freeze-drying to form a pure natural light gray powdery plant protease. This enzyme preparation contains not only proteolytic enzymes but also phosphatase, peroxidase, cellulase, and glycosidase, and has a pineapple aroma. It can efficiently decompose proteins, peptides, esters, and amides in tea leaves, transforming them into various amino acids and tea polysaccharides. The enzymatic hydrolysis process using bromelain in tea cultivation produces beneficial effects: through temperature-controlled tea cultivation, bromelain undergoes efficient enzymatic hydrolysis at a suitable temperature, decomposing proteins, peptides, esters, and amides in tea leaves and transforming them into various amino acids. This enhances the fresh and crisp taste, optimizes the quality, and overcomes the limitations of traditional tea cultivation processes, which require long processing times and are difficult to control in terms of quality.

[0012] The integrated withering, drying, and aging tea machine includes a withering, drying, and aging tea machine, a feeding and impurity removal conveyor belt, hot and cold air blowers, a temperature and humidity detector, and a PLC intelligent controller. The withering, drying, and aging tea machine is 3.5m long, 1.2m wide, and 1.7m high, with a three-layer stainless steel box structure. The first layer is a light and heat withering layer, the second layer is a cold air drying layer, and the third layer is an enzymatic aging tea layer. These three layers are connected sequentially by a stainless steel screen rotary conveyor belt, allowing the tea leaves to move automatically from the first layer downwards through light-changing and simulated light withering → cold air drying → enzymatic aging tea processing. The machine is also equipped with a feeding and impurity removal conveyor belt to remove mud, dust, hair, small insects, plant fragments, and metal debris from the withered buds and leaves, ensuring clean tea leaves are fed into the withering, drying, and aging tea machine, thus preventing these impurities from affecting the quality of the withering, drying, and aging process. In addition, the machine is equipped with a push-pull handle and casters for easy movement indoors and outdoors for different photothermal withering operations. Above the first photothermal withering layer is a retractable red light-changing net. This net is a double-layer composite net composed of a nano-quartz fiber mesh and a red fluorescent carbon dot light-converting film. This net can convert sunlight into red diffuse light with a wavelength of 680nm-740nm to wither the tea leaves. Above the first photothermal withering layer, there are also quartz tube infrared heating lamps and red and orange light-changing covers. The quartz tube infrared heating lamps utilize infrared radiation to generate heat energy, similar to the withering of tea leaves by sunlight. The red and orange light-changing covers are a red nano-quartz fiber film light-changing cover and an orange nano-quartz fiber film light-changing cover. These covers can convert the infrared light into red simulated diffuse light with a wavelength of 680-740nm or orange simulated diffuse light with a wavelength of 590-610nm to wither the fresh tea leaves. Eight quartz tube infrared heating lamps are arranged at intervals of 40-45cm and positioned 60-65cm above the photothermal withering layer. Simulated red diffused light is first used to enhance the activity of polyphenol oxidase, and then orange simulated diffused light is used to stabilize the activity of polyphenol oxidase, thereby improving the efficiency of photothermal withering.

[0013] Each conveyor belt has a feed trough at its inlet, and each trough contains a leaf-spreading roller to evenly distribute the tea leaves across the conveyor belts. The enzyme applicator is a centrifugal atomizing enzyme applicator, with the atomizing nozzle positioned 10-15 cm above the feed trough of the enzymatic tea-growing layer. The high-speed rotation of the centrifugal disc atomizes the bromelain solution into 5-10 micrometer ultrafine particles, which are then sprayed onto the fresh tea leaves. The leaf-spreading rollers include pine wood rollers and frosted ceramic rollers. Two pine wood rollers are positioned in the feed troughs of the heat-withering layer and the cold-air drying layer, respectively, and their clockwise rotation ensures the tea buds and leaves are evenly spread across the conveyor belt. The frosted ceramic leaf-shaping roller is a serrated leaf-shaping roller. One frosted ceramic leaf-shaping roller is arranged in the feeding trough of the tea-nourishing enzymatic hydrolysis layer. By using the clockwise rotation, the cell walls of the buds and leaves are broken, allowing the atomized exogenous enzymes to enter the inner layer of the buds and leaves for enzymatic hydrolysis.

[0014] The hot and cold air blower can provide hot air at 40-50℃ or switch to provide cold air at 10-12℃. The hot and cold air blower 7 is equipped with a set of cold air ducts 71 and a set of hot air ducts 72. The outlets of one cold air duct 71 and one hot air duct 72 are placed at the inlet of the photothermal withering layer 11. This allows for both cooling the tea leaves during outdoor photothermal withering and heating the tea leaves during indoor simulated photothermal withering, thus achieving temperature-controlled photothermal withering. The outlet of one cold air duct 71 is placed at the outlet of the cold air drying layer 12, simulating the natural temperature of spring when drying tea leaves by blowing cold air. The outlet of one of the cold air ducts 71 is placed at the inlet of the enzymatic tea-growing layer 13, and the outlet of one of the hot air ducts 72 is placed in the middle of the enzymatic tea-growing layer 13. The temperature of the enzymatic tea-growing layer is adjusted by blowing cold and hot air from different locations, allowing the tea-growing and enzymatic reactions to proceed in a suitable temperature environment. The temperature and humidity detector is a WiFi wireless temperature and humidity sensor. Three sensor probes are respectively arranged in the middle of the photothermal withering layer, the cold air drying layer, and the enzymatic tea-growing layer. The detected temperature and humidity signals are input into the controller to control the airflow of the cold and hot air ducts, thereby intelligently regulating the temperature and humidity of each layer. The technical effects of using an integrated withering, drying, and tea-nurturing machine and a frosted ceramic leaf-uniforming roller with enzyme-nurturing process are as follows: It realizes the integration and automation of withering, drying, and enzymatic tea-nurturing processes, and improves the production efficiency of these three processes. In particular, the use of a red light-changing net and a small infrared lamp with a light-changing cover can significantly improve the efficiency of photothermal withering and enhance quality. The use of a frosted ceramic leaf-uniforming roller with enzyme-nurturing breaks the cell walls of the buds and leaves, allowing bromelain to enter the inner layer for efficient enzymatic hydrolysis. At the same time, it can also promote the release of a large amount of flavor substances, which can solve the problem of the bland taste of Baihao Silver Needle tea due to lack of kneading.

[0015] 6) Temperature-controlled dynamic tea aging: The tea leaves, after being enzymatically hydrolyzed with bromelain, are fed into a temperature-controlled dynamic tea aging machine. The machine has three layers: a first hot air dynamic tea aging layer, a second hot air dynamic tea aging layer, and a third cold air dynamic tea aging layer. The settings are: the leaf thickness is 35-40 cm, the leaves are turned every 30-40 minutes for 1-1.5 minutes each time, and the enzymatic hydrolysis tea aging time is 6-9 hours. The tea aging temperature in the first hot air dynamic tea aging layer is 40-45℃ for 2-3 hours, the tea aging temperature in the second hot air dynamic tea aging layer is 35-38℃ for 3-4 hours, and the tea aging temperature in the third cold air dynamic tea aging layer is 15-20℃ for 1-2 hours. The beneficial effects of using a temperature-controlled tea-raising process with high, medium, and low temperatures are as follows: Through a bamboo fiber material screen conveyor belt, hot air is circulated three times to dynamically raise the tea leaves, which helps to dissipate the grassy smell, turns the color of the tea leaves to dark green or grayish-green, and shortens the traditional 5-7 day natural tea-raising time to less than 9 hours. At the same time, the hot air further enhances the enzymatic hydrolysis of exogenous bromelain, continuing to decompose proteins, peptides, esters, and amide compounds in the tea leaves without metal ion antagonism, thus improving quality.

[0016] 7) Sieving and Impurity Removal Machine: After temperature-controlled dynamic tea conditioning, the tea leaves are conveyed to the upper screen of the sieving and impurity removal machine for vibration and impurity removal before output. The sieving and impurity removal machine includes an upper vibrating screen and a lower vibrating screen. The upper vibrating screen has narrow mesh holes with a length of 15-25mm and a width of 8-9mm. The lower vibrating screen is wavy in shape and has round holes with a diameter of 1-3mm. The screen vibration frequency is set to 300-350 times / min, and the screen conveying capacity is 15-20kg / min. The rectangular mesh of the upper vibrating screen is used to collect and remove larger impurities such as fish leaves, yellow leaves, and stems remaining in the tea leaves. The round mesh of the lower vibrating screen is used to remove tea dust, dust, insect eggs, and other small impurities, thereby outputting clean and intact tea leaves from the tea outlet. The beneficial effects of using double-layer screens and different screen hole impurity removal processes: By using two different screen structures, rectangular screen holes and circular screen holes, the problem of existing tea shaking and sieving impurity removal machines being unable to remove fish leaves, scales, stipules, sticky small insects and insect eggs mixed in with single buds of Baihao Yinzhen tea can be solved. It can also improve the impurity removal efficiency by 30-40%, making its cleanliness as high as 95% or more.

[0017] 8) Dual-energy drying: After impurities are removed by the sieving and cleaning machine, the tea leaves are fed into a dual-energy roasting machine for electromagnetic and hot air drying. Settings: leaf thickness 4-6 cm, electromagnetic temperature 75-85°C, hot air temperature 50-55°C, roasting time 25-30 minutes, with the leaves turned over every 6-8 minutes for 1 minute each time. First, the electromagnetic radiation of the aluminum-titanium alloy ceramic roasting tank causes the moisture inside the tea leaves to overflow to the surface. Then, the flexible hot air from the air-source heat pump quickly dissipates the surface moisture, resulting in Baihao Yinzhen tea with a moisture content ≤6%, a silvery-white appearance, visible white down, and a fresh aroma. The beneficial effects of using the dual-heat drying process are as follows: electromagnetic drying technology is used to remove the internal moisture in time, and hot air is used to dry the moisture on the surface of the tea leaves in time, thereby improving the drying efficiency. Through the combined effect of electromagnetic radiation heat energy and air-source hot air, the drying process can not only replace and surpass the traditional charcoal oven baking process, but also maintain the quality characteristics of the tea leaves, which are white like silver and have white hairs. In particular, it can improve the thermal efficiency by 5-7%, shorten the baking time by 25-30%, reduce the drying cost by 15-20%, and avoid undesirable phenomena such as high-fire taste.

[0018] The electric dual-heat roasting machine includes a roasting tank, an electromagnetic device, an air-source heat pump, and a temperature and humidity monitoring and control device. The roasting tank is made of stainless steel on both sides, with an aluminum-titanium alloy outer wall and a ceramic-coated composite material inner wall. The aluminum-titanium alloy outer wall's high strength, rapid heat conduction, and uniform heat distribution improve the tea drying efficiency. The ceramic inner wall's non-stick properties solve the problem of tea juice sticking to the pan and scorching, affecting quality. The electromagnetic device includes a U-shaped groove fitted around the roasting tank. Three sets of electromagnetic heating coils are evenly arranged within the U-shaped groove. To prevent direct electromagnetic waves from scorching the silver needle tea, one-third of the roasting tank is embedded in the electromagnetic U-shaped groove at 0.8-1.1cm intervals. The intervals are filled with silicon carbide (carborundum) for radiation-resistant, intermittent heat conduction. This intermittent electromagnetic heat allows the moisture in the tea leaves to quickly dissipate to the surface for drying and promotes the volatilization of aromatic substances, enhancing aroma. The temperature-controlled dynamic tea-nurturing process further enhances the enzymatic hydrolysis of exogenous bromelain, generating more enzymatic products and improving quality. The dual-heat-energy roasting process, combining electromagnetic and air-source hot air, rapidly dries the tea leaves, increasing thermal efficiency. Vibrating screens with rectangular and circular apertures automatically remove impurities such as fish leaves, yellow leaves, stems, tea dust, dust, and insect eggs. The roasting tank, with its aluminum-titanium alloy outer wall and ceramic inner wall, along with intermittent electromagnetic heating, allows for rapid dissipation of moisture from the tea leaves, enhancing aroma without scorching the fine hairs of the silver needle tea.

[0019] The beneficial effects of this invention are as follows: This invention can improve the processing efficiency and quality of Baihao Yinzhen tea. Baihao Yinzhen tea produced using this method has a silvery-white appearance, prominent white down, a fresh and refreshing taste, and a delicate aroma. The use of a windmill-type withering machine with forward and reverse rotation and a two-stage addition of xylanase withering process allows the xylanase solution to be evenly added to the withered tea leaves. The blowing action generated by the forward and reverse rotation of the withering windmill facilitates dynamic withering and enzymatic hydrolysis, which not only accelerates the withering process and shortens the withering time, but also improves the efficiency of the enzymatic hydrolysis reaction. Furthermore, the xylanase efficiently breaks down the cell walls of the tea buds and leaves, allowing their contents to leak out. This solves the problem that Baihao Yinzhen tea, which is not rolled, has difficulty releasing its polyphenols, caffeine, amino acids, tea polysaccharides, and other compounds, resulting in a weak taste and poor brewing endurance. Simultaneously, it decomposes the non-starch polysaccharides (NSPS) in the tea leaves into low-polymerization xylooligosaccharides, adding a fresh, sweet, and mellow flavor to the tea soup and improving its clarity.

[0020] This invention employs an integrated withering, drying, and tea-nurturing machine for photothermal withering. On sunny days, a red nano-quartz fiber light-changing mesh converts sunlight into diffused red light to wither the tea leaves. This avoids scorching the tender buds with direct sunlight and utilizes the diffused red light to stimulate the activity of polyphenol oxidase in the tea leaves, causing oxidation, polymerization, and degradation reactions. This process transforms the tea leaves into a large amount of tea polysaccharides, amino acids, theaflavins, and aromatic substances, resulting in the unique aroma and taste of Baihao Yinzhen tea. On cloudy or rainy days and at night, a small infrared lamp and a light-changing cover are used to first convert the infrared light into simulated diffused red light to stimulate the activity of polyphenol oxidase, and then into simulated diffused orange light to stabilize the activity of polyphenol oxidase. Utilizing two different photothermal withering methods improves withering efficiency and overcomes the technical obstacle of not being able to perform photothermal withering on cloudy or rainy days and at night, enabling the production of Baihao Yinzhen tea around the clock.

[0021] By adding bromelain for dynamic enzymatic hydrolysis of tea, the grassy smell can be largely dissipated, the tea color can turn dark green or grayish-green, and the aging process can be accelerated, shortening the aging time by 75-80%. At the same time, hot air is used to further enhance the enzymatic hydrolysis of exogenous bromelain, decomposing a large amount of proteins, peptides, esters and amides in the tea leaves without metal ion antagonism, and transforming them into a variety of amino acids, adding to the fresh taste of Baihao Yinzhen tea and optimizing its quality.

[0022] Employing electromagnetic and air-source hot air drying technology, this process combines the combined effects of intermittent electromagnetic radiation heat and flexible air-source hot air to not only replace and surpass the traditional charcoal oven baking process, preserving the unique quality of its silvery-white appearance and visible white down, but also increasing thermal efficiency by 5-7%, shortening baking time by 25-30%, reducing drying costs by 15-20%, and avoiding undesirable phenomena such as a strong fire smell.

[0023] The present invention will now be described in more detail with reference to the accompanying drawings and embodiments. Attached Figure Description

[0024] Figure 1 This is a flowchart of the method steps in this invention.

[0025] Figure 2 This is a front view of the windmill-type spreading machine of the present invention.

[0026] Figure 3 This is a front view of the integrated withering, drying, and tea-nurturing machine of the present invention.

[0027] Figure 4 This is a front view of the withering and drying tea machine of the present invention.

[0028] Figure 5 This is a front view of the quartz tube infrared heating lamp and the red light-changing outer cover in this invention.

[0029] Figure 6 This is a front view of the temperature-controlled dynamic tea-nurturing machine of the present invention.

[0030] Figure 7 This is a side view of the five-finger-shaped material turner in this invention.

[0031] Figure 8 This is a front view of the sieving and impurity removal machine in this invention.

[0032] Figure 9 This is a front view of the dual-heat baking machine of the present invention.

[0033] Figure 10 This is a side view of the dual-heat baking machine of the present invention. Detailed Implementation

[0034] Example 1: As Figure 1-10 As shown, a method for preparing small-jar Baihao Yinzhen tea, when done on a sunny day, includes the following steps: 1) Raw material picking: Pick plump and heavy single buds, mainly of the Fuding Dahao tea variety, and remove fish-leaf scales and broken buds and leaves; 2) Xylanase hydrolysis withering: The picked tea leaves are fed into a windmill-type withering machine, and xylanase is added to the tea leaves for 360-degree rotating dynamic withering; the amount of xylanase added is 0.1-0.2% of the weight of the tea leaves, and the xylanase is diluted with water to prepare a xylanase solution with a concentration of 55-65% and a pH value of 5.3-5.5. Xylanase solution is sprayed onto the tea leaves through a rotary atomizing enzyme applicator located inside the tea inlet and a funnel-shaped atomizing enzyme applicator located above and on the opposite side of the tea inlet. The spreading windmill is set to rotate at 12-14 r / min and alternate between forward and reverse rotation. The leaves are naturally spread for 1.2-1.5 hours. The blowing action generated by the forward and reverse rotation promotes the addition of xylanase to break down the cell wall structure of the tea buds and leaves and penetrate deep into the inner layer to carry out enzymatic hydrolysis. This causes a large amount of flavor substances such as tea polyphenols, caffeine, amino acids, and tea polysaccharides to be released, solving the problem of the weak taste of Baihao Yinzhen tea and improving the clarity of the tea soup.

[0035] 3) Photothermal withering: After the tea leaves have been spread out, they are fed into the upper photothermal withering layer of the withering, drying, and nurturing tea machine. The machine is then moved to a sunny outdoor location. The red light-changing net on the photothermal withering layer is turned on to switch to red light for sunlight withering, and the cold air duct is turned on to control the temperature. The settings are: leaf roller speed 10-12 r / min, leaf thickness 12-15 cm, withering temperature 36-38°C, withering time 3-4 h, and leaves turned over for 1.5-2 min every 30 min to keep the water loss rate of buds and leaves between 12-14%. The red diffused light penetrates into the inner layer of tea cells, stimulating polyphenol oxidase activity and producing oxidation, polymerization, and degradation reactions, transforming into a large amount of tea polysaccharides, amino acids, theaflavins, and aromatic substances, forming the unique aroma and taste of Baihao Silver Needle.

[0036] 4) Cold air drying: The tea leaves after light and heat withering are fed into the second layer of cold air drying for cold air drying. The settings are: the leaf spreading roller speed is 10-11 r / min, the leaf thickness is 8-9 cm, the cold air drying time is 2-2.5 h, and the drying temperature is controlled between 22-24°C. Every 30 minutes, the leaves are turned for 1.5-1.7 minutes to allow the tea leaves to lose 4-5% of their moisture again and to release the grassy smell, humid heat and moisture generated during light and heat withering, making the leaves softer and the floral aroma initially appearing.

[0037] 5) Bromelain Enzymatic Hydrolysis for Tea Nourishment: After the tea leaves have been cooled in cold air, they are fed into the third layer of the enzymatic hydrolysis tea nourishment layer for enzymatic hydrolysis. The settings are as follows: the amount of bromelain added is 0.1-0.15% of the weight of the tea leaves, the leaf thickness is 35-36 cm, the enzymatic hydrolysis temperature is 38-40°C, the enzymatic hydrolysis time is 5-5.5 hours, and the leaves are turned over every 40 minutes for 1-1.5 minutes each time, so that the tea leaves lose 2-3% of their moisture again. This promotes the decomposition of proteins, peptides, esters and amides in the tea leaves by bromelain, which transforms them into a variety of amino acids to optimize the quality.

[0038] 6) Temperature-Controlled Dynamic Tea Cultivation: After the tea leaves have been enzymatically hydrolyzed with bromelain, they are fed into a temperature-controlled dynamic tea cultivation machine. This machine has three layers: a first hot air dynamic tea cultivation layer, a second hot air dynamic tea cultivation layer, and a third cold air dynamic tea cultivation layer. The settings are: the leaf thickness is 35-40 cm, the leaves are turned over every 30-40 minutes for 1-1.5 minutes each time, and the enzymatic hydrolysis tea cultivation time is 6-7 hours. Specifically, the tea cultivation temperature in the first hot air dynamic tea cultivation layer is 40-42℃ for 2-2.5 hours, the tea cultivation temperature in the second hot air dynamic tea cultivation layer is 35-36℃ for 3-3.2 hours, and the tea cultivation temperature in the third cold air dynamic tea cultivation layer is 15-18℃ for 1-1.3 hours. Through this three-layer temperature-controlled dynamic tea cultivation, the grassy smell is largely dissipated, the color of the tea leaves turns dark green or grayish-green, and the tea cultivation process is accelerated, shortening the cultivation time.

[0039] 7) Sieving and Impurity Removal Machine: After temperature-controlled dynamic tea conditioning, the tea leaves are conveyed to the upper screen of the sieving and impurity removal machine for vibration and impurity removal. The sieving and impurity removal machine includes an upper vibrating screen and a lower vibrating screen. The upper vibrating screen has narrow mesh holes with a length of 15-25mm and a width of 8-9mm. The lower vibrating screen is wavy in shape and has round holes with a diameter of 1-3mm. The screen vibration frequency is set to 300-350 times / min, and the screen conveying capacity is 15-20kg / min. The rectangular mesh of the upper vibrating screen is used to collect and remove larger impurities such as fish leaves, yellow leaves, and stems from the screen surface. The round mesh of the lower vibrating screen is used to remove residual tea dust, dirt, and other fine impurities. The clean and intact single-bud tea leaves on the lower screen are then fed into a dual-heat roasting machine for drying.

[0040] 8) Dual-energy drying: After the tea leaves are cleaned by the sieving and impurity removal machine, they are fed into the dual-energy roasting machine for electromagnetic and hot air drying; settings: leaf thickness is 8-10 cm, electromagnetic temperature is 75-80℃, hot air temperature is 50-54℃, roasting time is 15-17 min, the leaves are turned over once every 6-8 min, each time turning for 1 min, until the moisture content is ≤6%, the appearance is white like silver, the white hairs are visible, and the tea aroma is fresh and clear.

[0041] Example 2: A method for preparing small-canned Baihao Yinzhen tea, when done on cloudy or rainy days or at night without sunlight, includes the following steps: 1) Raw material picking: Pick plump and heavy single buds, mainly of the Fuding Dahao tea variety, and remove fish-leaf scales and broken buds and leaves; 2) Xylanase Enzymatic Hydrolysis During Withering: The harvested tea leaves are fed into a windmill-type withering machine, and xylanase is added to the tea leaves for dynamic withering via rotation. The amount of xylanase added is 0.2-0.3% of the weight of the tea leaves, and the xylanase is diluted with water to prepare a solution with a concentration of 55-65% and a pH of 5.3-5.5. The xylanase solution is sprayed onto the tea leaves through a rotary atomizing enzyme applicator located inside the tea inlet and a funnel-shaped atomizing enzyme applicator located above the withering windmill on the opposite side of the tea inlet. The withering windmill speed is set at 15-18 r / min, alternating between forward and reverse rotation. Natural withering takes 1.5-2 hours. By increasing the withering windmill speed by 2-3 r / min and extending the withering time by 0.2-0.4 hours, the added xylanase is encouraged to penetrate deeper into the inner layers of the tea leaves for enzymatic hydrolysis, ensuring efficient withering and enzymatic hydrolysis even on rainy days and at night.

[0042] 3) Photothermal withering: After the tea leaves have been spread out, feed them into the upper photothermal withering layer of the withering, drying, and aging tea-nurturing machine. Then move the machine indoors and set the following parameters: leaf thickness of 10-12 cm, turning claws turning leaves for 1.5-2 minutes every 30 minutes, withering temperature of 25-28℃. Then turn on the tubular double-ended quartz lamps on the photothermal withering layer. First, use a red light-changing cover to convert the infrared light to red simulated diffused light with a wavelength of 680-740nm for 3-4 hours of withering. Then, use an orange light-changing cover to convert the infrared light to orange simulated diffused light with a wavelength of 590-625nm for 2-3 hours of withering. Turn the leaves for 1.5-1.6 minutes every 30 minutes to control the moisture loss rate of the tea leaves between 12-13%. By using simulated red diffused light to enhance the activity of polyphenol oxidase for efficient photothermal withering, and then using simulated orange diffused light to stabilize the activity of polyphenol oxidase, the efficiency of photothermal withering is further improved. This overcomes the technical obstacle of not being able to carry out photothermal withering on cloudy or rainy days and at night, enabling the production of Baihao Yinzhen tea around the clock.

[0043] 4) Cold air drying: The tea leaves after light and heat withering are fed into the second layer of cold air drying for cold air drying. The settings are: the leaf spreading roller speed is 10-11 r / min, the leaf thickness is 7-8 cm, the cold air drying time is 2.5-3 h, and the drying temperature is controlled between 24-27℃. Every 30 min, the leaves are turned for 1.5-1.7 min to allow the tea leaves to lose 4-5% more moisture. By extending the drying time by 0.5 h and increasing the drying temperature by 2-3℃, the surface moisture, sunlight and grassy smell of the buds and leaves after withering are released more quickly, and the leaves become softer and the floral aroma is revealed.

[0044] 5) Bromelain Enzymatic Hydrolysis for Tea Nourishment: After the tea leaves have been cooled in cold air, they are fed into the third layer of the enzymatic hydrolysis tea nourishment layer for enzymatic hydrolysis. The settings are as follows: the amount of bromelain added is 0.15-0.3% of the weight of the tea leaves, the leaf thickness is 35-36 cm, the enzymatic hydrolysis temperature is 40-42°C, and the enzymatic hydrolysis time is 5.5-6 hours. The leaves are turned over every 40 minutes for 1-1.5 minutes each time, so that the tea leaves lose 2-3% of their moisture again. By increasing the amount of bromelain added and raising the tea nourishment temperature by 2-3°C, the enzymatic hydrolysis reaction is enhanced on rainy days and at night, transforming into various amino acids to optimize the quality.

[0045] 6) Temperature-Controlled Dynamic Tea Cultivation: After the tea leaves have been enzymatically hydrolyzed with bromelain, they are fed into a temperature-controlled dynamic tea cultivation machine. This machine has three layers: a first hot air dynamic tea cultivation layer, a second hot air dynamic tea cultivation layer, and a third cold air dynamic tea cultivation layer. The settings are: the leaf thickness is 34-36 cm, the leaves are turned every 30-40 minutes for 1-1.5 minutes each time, and the enzymatic hydrolysis tea cultivation time is 6-7 hours. Specifically, the tea cultivation temperature in the first hot air dynamic tea cultivation layer is 42-45℃ for 2.5-2.8 hours, the tea cultivation temperature in the second hot air dynamic tea cultivation layer is 36-38℃ for 3-3.2 hours, and the tea cultivation temperature in the third cold air dynamic tea cultivation layer is 18-20℃ for 1 hour. Through this three-layer temperature-controlled dynamic tea cultivation, the grassy smell is largely dissipated, the color of the tea leaves turns dark green or grayish-green, and the tea cultivation process is accelerated, shortening the cultivation time. By increasing the tea-aging temperature by 2-4℃, the enzymatic hydrolysis of bromelain in the tea is enhanced, causing the grassy smell to dissipate, the color of the tea leaves to turn dark green or grayish-green, and the aging time to be shortened.

[0046] 7) Sieving and Impurity Removal Machine: After temperature-controlled dynamic tea conditioning, the tea leaves are conveyed to the upper screen of the sieving and impurity removal machine for vibration and impurity removal before output. The sieving and impurity removal machine includes an upper vibrating screen and a lower vibrating screen. The upper vibrating screen has narrow mesh holes with a length of 15-25mm and a width of 8-9mm. The lower vibrating screen is wavy in shape and has round holes with a diameter of 1-3mm. The screen vibration frequency is set to 300-350 times / min, and the screen conveying capacity is 15-20kg / min. The rectangular mesh of the upper vibrating screen is used to collect and remove larger impurities such as fish leaves, yellow leaves, and stems from the screen surface. The round mesh of the lower vibrating screen is used to remove residual tea dust, dirt, and other fine impurities. The clean and intact single-bud tea leaves on the lower screen are then fed into a dual-heat roasting machine for drying.

[0047] 8) Dual-energy drying: After impurities are removed by the sieving and cleaning machine, the tea leaves are fed into a dual-energy drying machine for electromagnetic and hot air drying. Settings: leaf thickness 8-10 cm, electromagnetic temperature 80-85℃, hot air temperature 54-56℃, drying time 17-20 min, turning the leaves every 6-8 min for 1 min each time, drying until the moisture content is ≤6%, yielding Baihao Yinzhen tea. By increasing the electromagnetic temperature by 5-6℃, the hot air temperature by 2-3℃, and extending the drying time by 2-3 min, the problem of low temperatures on rainy days and at night is addressed, resulting in Baihao Yinzhen tea with a silvery-white appearance, visible white down, and a fresh aroma.

[0048] The specific equipment structure involved in each step is described as follows: The windmill-type tea-spreading machine 1 includes a tea-spreading frame 11, a tea-spreading windmill 12 mounted on the frame 11 and capable of forward and reverse rotation, a tea inlet hopper 13 located above one side of the windmill 12, and a receiving device 14 located below the other side. A set of tea-spreading mesh boxes 15 are evenly arranged along the circumference of the windmill 12. Each mesh box 15 is equipped with a cover 16, and both the mesh boxes 15 and the cover 16 are made of 18-20 mesh stainless steel. The tea leaves are placed inside the mesh boxes 15, and the forward and reverse rotation of the windmill 12 drives the tea leaves within the mesh boxes 15 to dynamically spread them. The airflow generated by the rotation of the windmill 12 blows towards the tea leaves in the mesh boxes 15, increasing the spreading speed. Simultaneously, the forward and reverse rotation of the windmill 12 mixes the tea leaves within the mesh boxes 15.

[0049] In order to enable the spreading winch 12 to rotate clockwise and counterclockwise, the rotating shaft of the spreading winch 12 is connected to the forward and reverse frequency modulation motor 17 through a rotating gear, and the forward and reverse frequency modulation motor 17 is programmed by the control system. The forward and reverse frequency modulation motor 17 drives the rotating shaft to rotate, thereby driving the spreading winch 12 to spread green in both forward and reverse directions and to rotate and spread green at different speeds.

[0050] To ensure the uniformity of xylanase spraying and mixing with tea leaves, a 360-degree rotating atomizing enzyme applicator 18 is installed inside the tea inlet hopper 13. The rotating atomizing enzyme applicator 18 includes a rotating atomizing nozzle. This allows for the circumferential spraying of xylanase atomized liquid onto the spread tea leaves in the tea inlet hopper 13, ensuring the enzyme solution is evenly sprayed into the spread tea leaves. Above the spreading winch 12 on the other side of the tea inlet hopper 13, a funnel-shaped atomizing enzyme applicator 19 is arranged to spray xylanase atomized liquid downwards a second time onto the tea leaves in the spreading mesh box 15 below. The rotating airflow and mixing action generated by the forward and reverse rotation of the spreading winch 12 promote the added xylanase solution to penetrate deep into the inner layer of the tea leaves for enzymatic hydrolysis.

[0051] The integrated withering, drying, and tea-nurturing machine 2 includes a withering, drying, and tea-nurturing machine 21, a feeding and impurity removal conveyor belt 210 installed at the feeding end of the withering, drying, and tea-nurturing machine 21, a hot and cold air fan 27 that provides hot and cold air to the withering, drying, and tea-nurturing machine 21, and a PLC intelligent controller 29.

[0052] The withering and tea-nurturing machine 21 is 3.5m long, 1.2m wide, and 1.7m high, with a three-layer stainless steel box structure. The first layer is a light and heat withering layer 211, the second layer is a cold air withering layer 212, and the third layer is an enzymatic tea-nurturing layer 213. The bottom of the light and heat withering layer 211, the cold air withering layer 212, and the enzymatic tea-nurturing layer 213 are all equipped with stainless steel screen conveyor belts 22. The three layers are connected sequentially by the stainless steel screen conveyor belts 22, so that the tea leaves move from the first layer down layer automatically to carry out light-changing and simulated light withering → cold air withering → enzymatic tea-nurturing operations.

[0053] The machine is also equipped with a feeding and impurity removal conveyor belt 210. The feeding end of the feeding and impurity removal conveyor belt 210 is provided with a tea hopper 2101. The feeding and impurity removal conveyor belt 210 is an inclined screen conveyor belt. The feeding and impurity removal conveyor belt 210 is provided with a suction hood 2102. The suction hood 2102 is connected to a suction pipe 2103. Below the suction hood 2102, there is also a leaf turner 2104 for turning the tea leaves. The leaf turner 2104 turns the tea leaves and, under the suction of the suction pipe 2103, removes the dust, hair, small insects, plant fragments, and grassy smell. The inclined screen conveyor belt is a 10-12 mesh stainless steel screen conveyor belt, arranged at an upward inclination of 15-20 degrees. It can further remove residual mud, insect eggs, tea dust, metal rust and other small impurities from the tea leaves during the process of conveying the tea leaves to the photothermal withering layer, so as to ensure that the clean buds and leaves are fed into the withering layer for photothermal withering and avoid affecting the product quality.

[0054] The withering and drying tea machine 21 is also equipped with a push-pull handle 217 and casters 218 for easy movement indoors and outdoors for different photothermal withering operations. A retractable red light-changing net 23 is installed above the first photothermal withering layer 211. This red light-changing net 23 is a double-layer composite net composed of a nano-quartz fiber mesh and a red fluorescent carbon dot light-converting film. This net can convert sunlight into red diffused light with a wavelength of 680nm-740nm to wither the tea leaves. Above the first photothermal withering layer 211, a quartz tube infrared heating lamp 24 and a detachable light-changing cover 25 are also arranged. The light-changing cover 25 includes both red and orange covers. The quartz tube infrared heating lamp 24 generates heat energy using infrared radiation, similar to the withering of tea leaves by sunlight. The red light-changing cover 25 is a red nano-quartz fiber film light-changing cover, and the orange light-changing cover 25 is an orange nano-quartz fiber film light-changing cover. This variable light cover can convert infrared light into simulated red diffused light with a wavelength of 680-740nm or simulated orange diffused light with a wavelength of 590-610nm to wither fresh tea leaves. Eight quartz tube infrared heating lamps 24 are arranged at intervals of 40-45cm above the photothermal withering layer 211 at a distance of 60-65cm. The simulated red diffused light is first used to enhance the activity of polyphenol oxidase, and then the simulated orange diffused light is used to stabilize the activity of polyphenol oxidase, so as to improve the efficiency of photothermal withering.

[0055] Each layer of stainless steel mesh conveyor belt 22 has a feeding trough 219 at its inlet, and a leaf-spreading roller is installed in each feeding trough 219 to evenly spread the tea leaves on each layer of the conveyor belt. The enzyme adder 26 is a centrifugal atomizing enzyme adder. The atomizing enzyme adder nozzle is arranged 10-15cm above the feeding trough 219 of the enzymatic tea-growing layer 213. The high-speed rotation of the centrifugal turntable atomizes the bromelain solution into ultrafine particles of 5-10 micrometers and sprays them onto the fresh tea leaves. The leaf-spreading rollers include pine wood leaf-spreading rollers 215 and frosted ceramic leaf-spreading rollers 216. Two pine wood leaf-spreading rollers 215 are arranged in the feeding troughs 219 of the light and heat withering layer 211 and the cold air drying layer 212, respectively. The clockwise rotation makes the buds and leaves spread evenly on the conveyor belt. The frosted ceramic leaf-shaping roller 216 is a serrated leaf-shaping roller. One frosted ceramic leaf-shaping roller 216 is arranged in the feed trough 219 of the tea-nourishing enzymatic hydrolysis layer 213. By using the clockwise rotation, the cell walls of the buds and leaves are broken, so that the atomized exogenous enzymes can enter the inner layer of the buds and leaves to carry out enzymatic hydrolysis.

[0056] The hot and cold air blower 27 can provide hot air at 40-50℃ or switch to provide cold air at 10-12℃. The hot and cold air blower 27 is equipped with a set of cold air ducts 271 and a set of hot air ducts 272. The outlets of one cold air duct 271 and one hot air duct 272 are placed at the inlet of the photothermal withering layer 211. This allows for both cooling the tea leaves during outdoor photothermal withering and heating the tea leaves during indoor simulated photothermal withering, thus achieving temperature-controlled photothermal withering. The outlet of one cold air duct 271 is placed at the outlet of the cold air drying layer 212, simulating the natural spring temperature for drying the tea leaves by blowing cold air. One of the cold air ducts 271 has its outlet placed at the inlet of the enzymatic tea-growing layer 213, and the other of the hot air ducts 272 has its outlet placed in the middle of the enzymatic tea-growing layer 213. By blowing cold and hot air from different locations, the temperature of the enzymatic tea-growing layer is adjusted, allowing the tea-growing and enzymatic reactions to proceed in a suitable temperature environment. The temperature and humidity detector 28 is a WiFi wireless temperature and humidity sensor. Three sensor probes are respectively arranged in the middle of the photothermal withering layer 211, the cold air drying layer 212, and the enzymatic tea-growing layer 213. The detected temperature and humidity signals are input to the PLC intelligent controller 29 to control the airflow of the cold and hot air ducts, thereby intelligently regulating the temperature and humidity of each layer.

[0057] The temperature-controlled dynamic tea-nurturing machine 3 has a three-layer trough structure and is equipped with three screen conveyor belts 34. The three screen conveyor belts 34 divide the trough into three independent tea-nurturing layers, from top to bottom: the first hot air dynamic tea-nurturing layer 31, the second hot air dynamic tea-nurturing layer 32, and the third cold air dynamic tea-nurturing layer 33, so as to use different temperatures for dynamic tea nurturing. The screen conveyor belts 34 are 15-20 mesh antibacterial bamboo fiber screen conveyor belts. This conveyor belt can transport tea leaves with air, without "hot stuffiness", and will not breed microorganisms and bacteria that affect the quality of tea nurturing.

[0058] To enable automated tea turning, five-finger-shaped tea turners 39 are installed at intervals of 1.1-1.3m above each layer of the screen conveyor belt 34. These five-finger-shaped tea turners 39 are made of birch wood and simulate the movement of tea leaves by hand, overcoming the technical obstacle of manually turning tea leaves on multi-layer conveyor belts. The temperature-controlled dynamic tea-nurturing machine 3 is also equipped with hot and cold air fans 35. These hot and cold air devices 35 are KFRD-51LW / Y1-4 type air-source heat pump fans. This machine utilizes the reverse Carnot cycle principle and air-source heat pump technology to extract heat energy from the air and convert it into high-temperature heat energy. Furthermore, the machine has a heat energy conversion mode, with a cold air chamber and a hot air chamber, providing cold and hot air respectively. It also has one hot air outlet and one cold air outlet, allowing for independent output of both cold and hot air, making it a dual-purpose hot and cold air device. Two hot air pipes 352 are connected to the hot air outlet, and two cold air pipes 351 are connected to the cold air outlet. Flow control valves 353 are installed on both the hot air pipes 351 and 352. The outlet of one hot air pipe 352 is positioned at the inlet of the first dynamic tea-cultivating layer 31 to blow 40-45℃ hot air into the trough for high-temperature dynamic tea cultivation. One hot air pipe 352 and one cold air pipe 351 are positioned at the inlet of the second hot air dynamic tea-cultivating layer 32. By adjusting the airflow of the hot air pipe 352 and the cold air pipe 351, a mixed airflow is formed to blow 35-38℃ hot air into the trough for medium-temperature dynamic tea cultivation. One cold air pipe 351 is positioned at the outlet of the third cold air dynamic tea-cultivating layer 33 to blow 15-20℃ cold air in the opposite direction, promoting the faster dissipation of grassy and humid heat from the piled tea leaves.

[0059] The screening and impurity removal machine 4 includes a set of support legs 46 mounted on the frame 401, and a vibrating frame 47 mounted on the support legs 46. The vibrating frame 47 is provided with an upper vibrating screen 41 and a lower vibrating screen 42 located below the upper vibrating screen 41. The upper vibrating screen 41 and the lower vibrating screen 42 are arranged in the vibrating frame 47 at a downward tilt of 6-8 degrees for inclined impurity removal and conveying.

[0060] The upper stepped vibrating screen 41 and the lower vibrating screen 42 are supported on the vibrating frame 47 by a set of vibrating springs 410. The vibration of the vibrating frame 47 drives the upper vibrating screen 41 and the lower vibrating screen 42 to vibrate together, thereby achieving the screening of tea leaves. To drive the vibration of the vibrating frame 47, a vibrator 48 is provided on the vibrating frame 47, and a damping spring 49 is provided between the support foot 46 and the vibrating frame 47. The vibrator 48 is preferably a vibrating motor.

[0061] The upper vibrating screen 41 has narrow mesh holes with a length of 15-25mm and a width of 8-9mm. The lower vibrating screen 42 is wavy in shape and has round holes with a diameter of 1-3mm. When the large impurities of the Baihao Yinzhen tea that has been removed from the upper stepped vibrating screen 41 fall onto the lower vibrating screen 42 for vibration and sieving, the remaining mud, dust, tea dust and other small impurities will be quickly sieved through the round mesh holes, so that clean and uniform Baihao Yinzhen tea is output from the tea outlet.

[0062] The dual-heat roasting machine 5 includes a roasting tank 51 mounted on a frame 501. An electromagnetic device 52 is provided below the roasting tank 51 to provide electromagnetic radiation heat to the tea leaves in the tank. An air-source heat pump 53 is provided at the feed end of the roasting tank 51 to blow air into the tank. A temperature and humidity detection device 54 is also provided inside the roasting tank 51 to monitor the temperature inside the tank.

[0063] The baking tank 51 is a U-shaped tank structure with a length of 2.6m, a width of 1.2m, and a depth of 0.9m. The baking tank 51 includes a U-shaped bottom 511 and tank sides 512 located on both sides of the bottom 511. The tank sides 512 are made of stainless steel. The bottom 511 has a double-layer structure, with the inner wall made of ceramic material (ceramic material layer 5111) and the outer wall made of aluminum-titanium alloy composite material (aluminum-titanium alloy composite material layer 5112). The high strength, high flexibility, fast heat conduction, and uniform heat distribution of aluminum-titanium alloy are utilized to improve the drying efficiency and heat uniformity of the tea. The non-stick properties of the ceramic inner wall can solve the problem of tea juice sticking to the pan and charring during baking, which affects the quality.

[0064] The electromagnetic device 52 includes a U-shaped groove 521 fitted outside the baking tank 51. Three sets of electromagnetic heating coils 522 are installed inside the U-shaped groove 521, and an electromagnetic generator 523 is connected to each electromagnetic heating coil 522. The three sets of electromagnetic heating coils 522 are evenly laid out in the U-shaped groove 521 at intervals of 0.7-0.8m. The high temperature of 130-150℃ electromagnetic radiation generated by electromagnetic induction heats the tea leaves in the baking tank 51. To prevent direct electromagnetic waves from scorching the tea leaves, the lower third of the baking tank 51 is placed inside the U-shaped groove 521, with a gap of 0.8-1.1cm between the U-shaped groove 521 and the baking tank 51. This gap is filled with silicon carbide (diamond sand) 56 for intermittent low-radiation heat conduction, which not only blocks electromagnetic waves from scorching the tea leaves but also keeps the tea warm, improves drying efficiency, and promotes the volatilization of aromatic substances, enhancing the aroma.

[0065] The air-source heat pump 53 is a KFRD-51LW / Y1 type air-source heat pump. This machine also has the function of switching between hot and cold air modes. In hot air mode, it can directly blow 50-55℃ hot air into the roasting tank 51. If the roasting temperature inside the tank 51 is too high, it can switch to cold air mode, blowing 15-20℃ cold air to cool it down, achieving dual-purpose functionality. The hot air pipes 531 of the air-source heat pump 53 are arranged side-by-side at the inlet end of the roasting tank 51 to blow 50-55℃ hot air into the tank. The force of the hot air promotes the evaporation of moisture from the tea leaves, achieving rapid drying.

[0066] 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 method for preparing a small tin white tip silver needle tea, characterized in that, The method comprises the following steps: 1) raw material picking: picking the Fuding Dahao tea variety as the main fat and strong single bud; 2) xylanase enzymolysis and spreading: inputting the picked tea leaves into a windmill type spreading machine and adding xylanase to the tea leaves for rotating dynamic spreading; 3) light and heat withering: inputting the spreaded tea leaves into the upper light and heat withering layer of a withering, spreading and tea processing integrated machine for light and heat withering, setting: the leaf thickness is 10-12 cm, the leaf turning time is 1.5-2 min, the light and heat withering time is 3-7 h, and the temperature is 25-38 C, so that the tea leaf moisture loss rate is controlled between 12-14%; 4) cold air spreading: inputting the light and heat withered tea leaves into the second layer of cold air spreading layer for cold air spreading, setting: the leaf thickness is 7-9 cm, the spreading time is 2-3 h, the spreading temperature is 20-25 C, and the leaf turning time is 1.5-2 min every 35 min, so that the spreaded tea leaves are dehydrated by 3-5% again; 5) bromelain enzymolysis and tea processing: inputting the cold air spreaded tea leaves into the third layer of enzymolysis and tea processing layer for enzymolysis and tea processing, setting: the bromelain addition amount is 0.1-0.3% of the tea leaf weight, the leaf thickness is 35-40 cm, the enzymolysis and tea processing temperature is 38-42 C, the enzymolysis and tea processing time is 5-6 h, and the leaf turning time is 1-1.5 min every 40 min, so that the tea leaves are dehydrated by 2-3% again; 6) temperature control dynamic tea processing: inputting the bromelain enzymolysis and tea processed tea leaves into a temperature control dynamic tea processing machine for temperature control dynamic tea processing, the temperature control dynamic tea processing machine is provided with three layers, which are a first hot air dynamic tea processing layer, a second hot air dynamic tea processing layer and a third cold air dynamic tea processing layer in sequence; setting: the leaf thickness is 34-40 cm, the leaf turning time is 1-1.5 min every 30-40 min, and the enzymolysis and tea processing time is 6-9 h; 7) impurity removal by a screening and impurity removal machine: inputting the temperature control dynamic tea processed tea leaves into the upper screen of a screening and impurity removal machine for vibration impurity removal and output; the screening and impurity removal machine comprises an upper vibration screen and a lower vibration screen, the upper vibration screen is provided with fine and narrow screen holes with a hole diameter of 15-25 mm and a hole width of 8-9 mm, and the lower vibration screen is in a whole wave shape and is provided with round holes with a hole diameter of 1-3 mm; setting: the screen vibration frequency is 300-350 times / min, and the screen conveying amount is 15-20 kg / min; 8) double heat energy drying: inputting the screened and impurity removed tea leaves into a double heat energy baking machine for electromagnetic and hot air drying; setting: the leaf thickness is 8-10 cm, the electromagnetic temperature is 75-85 C, the hot air temperature is 50-56 C, the baking time is 15-20 min, the leaf turning time is 1 min every 6-8 min.

2. The method of preparing small tinny white hair silver needle tea according to claim 1, characterized in that: The xylanase addition amount in step 2) is 0.1-0.3% of the tea leaf weight, and the xylanase is configured into a xylanase solution with a concentration of 55-65%, and a pH value of 5.3-5.

5.

3. The method of preparing small tinny white hair silver needle tea according to claim 1, characterized in that: The windmill type spreading machine comprises a spreading machine frame, a spreading windmill installed on the spreading machine frame, a group of spreading net boxes uniformly arranged on the spreading windmill in the circumferential direction, a tea inlet hopper arranged at one end of the spreading windmill, a 360-degree rotating atomizing enzyme adding device arranged in the tea inlet hopper, and a horn-shaped atomizing enzyme adding device arranged above the other side of the spreading windmill relative to the tea inlet hopper.

4. The method of preparing small tinny white tip silver needle tea according to claim 1, characterized in that: In step 3), when it is sunny, the withering and spreading machine is placed outdoors, the red light changing net at the top is opened, and red light is converted for solar withering. Settings: the thickness of the spread leaves is 12-15 cm, the turning claw turns the leaves every 30 min, the turning time is 1.5-2 min, the light and heat withering time is 3-4 h, and the withering temperature is 36-38℃; when it is rainy and at night, the withering and spreading machine is placed indoors, the thickness of the spread leaves is 10-12 cm, the turning claw turns the leaves every 30 min, the turning time is 1.5-2 min, the withering temperature is 25-28℃, the red simulated diffuse light with a wavelength of 680-740 nm is used for withering for 3-4 h, and then the orange simulated diffuse light with a wavelength of 590-625 nm is used for withering for 2-3 h.

5. The method of preparing small tinny white hair silver needle tea according to claim 1, characterized in that: In step 6), the first hot air dynamic tea growing layer has a tea growing temperature of 40-45℃ and a time of 2-3 h, the second hot air dynamic tea growing layer has a tea growing temperature of 35-38℃ and a time of 3-4 h, and the third cold air dynamic tea growing layer has a tea growing temperature of 15-20℃ and a time of 1-2 h.

6. The method of preparing small tinny white hair silver needle tea according to claim 1, characterized in that: The double-thermal-energy baking machine comprises a baking tank body, an electromagnetic device arranged below the baking tank body to provide electromagnetic radiation heat to the tea leaves in the tank, an air energy air blower arranged at the feeding end of the baking tank body to blow air into the tank, and a temperature and humidity detection device arranged in the baking tank body.

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