Preparation method of Sanjiang Dong tea

Abstract

The invention belongs to the technical field of tea processing, and particularly relates to a preparation method of Sanjiang Dong tea, which specifically comprises the following operation steps: (1) picking fresh leaves; (2) spreading: placing the picked fresh tea leaves in a tea withering device for spreading treatment; (3) performing fixation: performing fixation treatment on the spread tea leaves by using a fixation device, and ensuring that the fixation temperature is not too high or too low in the fixation process; (4) first twisting; (5) pile fermentation; (6) re-rolling the tea leaves subjected to pile fermentation; and (7) drying. According to the invention, the quality of the Sanjiang Dong tea (dark tea) is effectively improved by controlling the fixation process and optimizing the fixation structure equipment.

Description

Technical Field

[0001] The invention belongs to the technical field of tea processing, and particularly relates to a preparation method of Sanjiang Dong tea. Background Art

[0002] Dark tea is one of the traditional teas in China, mainly produced in Hunan, Hubei, Sichuan, Yunnan and other places. It is famous for its unique fermentation process and flavor. The fermentation process of dark tea is a post-fermentation, that is, the tea leaves are piled and fermented for a period of time after picking, thus forming its unique color and flavor. Dark tea contains a variety of ingredients that are beneficial to the human body and has the following health benefits: (1) Antioxidant effect: The active substances such as tea polyphenols in dark tea have antioxidant properties, which can remove free radicals in the body, slow down the aging of cells, and protect the body from oxidative damage. (2) Lowering blood lipids and weight loss: Dark tea can inhibit fat absorption, promote the excretion of fatty acids, and help lower blood lipids and body weight. (3) Lowering blood sugar: The tea polysaccharide complex in dark tea has a blood sugar lowering effect, which helps improve sugar metabolism and prevent and treat diabetes. (4) Lowering blood pressure: Specific amino acids such as theanine and other ingredients in dark tea can promote vasodilation, thereby lowering blood pressure. (5) Antibacterial and anti-inflammatory: Ingredients such as theaflavins and thearubigins in dark tea have inhibitory effects on a variety of bacteria, helping to prevent and treat oral and skin infections. (6) Aid digestion: Dark tea can promote the secretion of gastric juice and saliva, aid digestion, and is especially suitable for meat eaters, as it helps to relieve greasiness and digest food. (7) Anti-cancer effect: Dark tea has an inhibitory effect on tumor cells, and regular drinking may help prevent and fight cancer. (8) Diuretic and detoxifying: The caffeine in dark tea has a diuretic effect, which helps to promote the excretion of waste and toxins in the body. (9) Nutritional supplement: Dark tea contains a variety of vitamins and minerals, and is an important source of nutrition for people whose diet lacks vegetables and fruits. (10) Anti-aging: The antioxidant components in dark tea help to delay cell aging and have anti-aging effects. Therefore, many people love to drink dark tea.

[0003] The study found that each step in the production of black tea has an impact on the quality of black tea. Among them, the process of killing green tea is very important, mainly for the following reasons: inhibiting enzymatic oxidation, evaporating water, promoting aroma formation, and preparing for subsequent processes. (1) Inhibiting enzymatic oxidation: The main purpose of killing green tea is to destroy and passivate the oxidase activity in fresh leaves through high temperature, inhibiting the enzymatic oxidation of tea polyphenols in fresh leaves. This step is crucial to maintaining the quality and flavor of tea, because enzymatic oxidation can cause tea to deteriorate and affect its taste and aroma. (2) Evaporating water: During the killing green tea process, part of the water in the fresh leaves is evaporated through high temperature treatment, making the tea leaves softer and increasing the toughness of the tea leaves, which is convenient for subsequent rolling and forming. This step has a direct impact on the shape and appearance of the tea leaves and is a key link in the tea processing process. (3) Promoting aroma formation: Killing green tea can also emit a green smell and promote the formation of a good aroma. This step plays an important role in improving the overall aroma and taste of the tea, allowing the tea to emit a more pleasant aroma during the subsequent brewing process. (4) Prepare for the subsequent processes: As one of the initial processing steps for green tea, yellow tea, black tea, oolong tea, etc., killing green tea prepares for the subsequent processes of rolling, piling, re-rolling, drying, etc. These subsequent processes have a direct impact on the color, aroma, taste, and shape of the tea leaves. Therefore, the quality of killing green tea is directly related to the quality of the final tea leaves.

[0004] In summary, killing green tea is an indispensable part of the dark tea processing. It is the process of passivating the endogenous enzymes of the tea leaves during the dark tea processing, which provides the premise for the tea leaves to utilize the microbial extracellular enzymes and the effects of moisture and heat to promote the oxidation of the tea leaves' contents during the pile fermentation process. It is not only related to the quality and flavor of the tea leaves, but also affects the appearance and aroma of the tea leaves. Therefore, the control and optimization of the killing green process is of great significance to improving the overall quality of dark tea. Summary of the invention

[0005] The invention aims to provide a preparation method of Sanjiang Dong tea, which effectively reduces production energy consumption and improves the quality of Sanjiang Dong tea (dark tea) by controlling the withering process and optimizing the structural equipment of withering.

[0006] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing Sanjiang Dong tea specifically comprises the following steps:

[0008] (1) Picking fresh leaves: Picking one bud, two or three leaves of summer and autumn tea leaves manually or by machine, picking is done between 8-11 am and 4-6 pm;

[0009] (2) Spreading: Put the picked summer and autumn tea into the tea withering device for spreading, and the spreading thickness shall not exceed 30 cm;

[0010] The tea withering device comprises a withering trough, which comprises a trough body and a chain plate type conveyor device arranged at the upper inner side of the trough body; the chain plate type conveyor device comprises a plurality of chain plates for placing tea leaves, each of which is provided with a plurality of ventilation holes; a conveyor belt for receiving tea leaves and conveying the tea leaves to the next process is arranged at the discharge end of the chain plate type conveyor device;

[0011] (3) Fixing: Use a fixing device to fix the tea leaves after spreading, and ensure that the fixing temperature is not too high or too low during the fixing process;

[0012] The tea-tea-fixing device comprises a hot air fixing machine, a steam fixing machine and a steam furnace, wherein the steam furnace is connected to a steam chamber of the steam fixing machine through a steam pipe, the discharge end of the hot air fixing machine is connected to a feed end of the steam fixing machine through a first conveyor belt, and the exhaust port of the hot air fixing machine is connected to the steam chamber of the steam fixing machine through an exhaust pipe; the temperature of the hot air fixing machine is controlled at 260-280° C., and the temperature of the steam fixing machine is controlled at 200-240° C.;

[0013] (4) Preliminary twisting: After withering, the tea leaves are twisted while still hot to form strips; the twisting is performed by light pressing and the twisting time is 20-30 minutes;

[0014] (5) Piling: The height of the pile shall not exceed 1m, and the pile shall be placed in a dark pile-making room with a temperature of 30-45°C and a humidity of 80%-90%. The time of the pile-making is 8-16 hours.

[0015] (6) re-kneading the tea leaves after the fermentation;

[0016] (7) Drying: Place the tea leaves after re-kneading in an environment with a temperature of 40°C and a humidity of 30% to dry until the moisture content of the tea leaves is less than 9.0%.

[0017] It is further explained that the left and right ends of the chain plates of the chain-plate conveyor device are hidden in the trough body; the top surface of the chain-plate conveyor device is provided with baffles on the other three sides except the discharge end, and the baffles are movably connected to a number of chain plates and fixedly connected to the trough body of the withering trough.

[0018] It is further explained that a control switch is provided on the trough body of the withering trough, and the control switch, the chain plate conveyor device and the conveyor belt are all electrically connected to the controller, and the controller is a PLC.

[0019] It is further explained that the conveying direction of the conveyor belt is arranged perpendicular to the conveying direction of the chain-plate conveyor device; the number of the withering troughs is greater than two, and the number of the conveyor belts is one.

[0020] Further description, the steam fixing machine includes a frame and a second conveyor belt, the steam chamber is arranged on the frame, the second conveyor belt is horizontally arranged on the frame and passes through the steam chamber; the steam chamber includes a trough body and a top cover, the trough body is arranged on the frame, and its top and left and right sides are both open structures, the top cover is closed on the top of the trough body, and a discharge port is arranged on the top of the top cover.

[0021] It is further explained that the top cover is detachably connected to the tank body, and the discharge port is provided with a discharge valve; the bottom of the tank body is connected to the exhaust pipe and the steam pipe through a mixing pipe assembly.

[0022] Further description, the mixing tube assembly includes a main tube and at least two branch tubes, the main tube is connected to the trough body through at least two branch tubes, and the middle part of the main tube is connected to the exhaust pipe and the steam pipe; a third conveyor belt is arranged below the tea scraping structure.

[0023] It is further explained that the first conveyor belt and the third conveyor belt are both climbing conveyor belts.

[0024] It is further explained that a material collecting trough is provided at the discharge end of the second conveyor belt, and the material collecting trough is installed on the frame and is located below the scraper.

[0025] Due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0026] The Sanjiang Dong tea (dark tea) produced by the process steps of the present invention can effectively improve the tea color, aroma and taste.

[0027] In the process of withering, the black tea prepared by using the withering equipment designed by our team before withering has better color, aroma, taste and shape than the black tea prepared by conventional withering machines.

[0028] This team combines the hot air fixing machine with the steam fixing machine. After the tea leaves are fixed with hot air, they are then steam fixed. On the one hand, this can reduce the working temperature of the hot air fixing machine and avoid the phenomenon of scorched leaves and scorched edges during the fixing process of the tea leaves. On the other hand, steam fixing is beneficial to passivate the activity of enzymes and inhibit enzymatic oxidation. The combination of the two also shortens the steam fixing time and can avoid the problem of excessive water content in the tea leaves. In addition, hot air fixing and steam fixing are carried out separately, which is conducive to controlling and adjusting the fixing temperature and avoiding the fixing temperature being too high or too low. Only a simple modification needs to be made to the existing fixing machine to avoid the problem of waste of resources and reduce the cost of equipment procurement for enterprises.

[0029] Withering is required before withering. In actual operation, we found that the spreading of fresh leaves requires a large space, and the traditional spreading process requires multiple people to operate. First, manual processing may cause fresh leaves to be scratched and damaged by equipment, resulting in enzymatic oxidation of some leaves. Second, manual transportation is time-consuming, labor-intensive, costly, and time-consuming. Therefore, the applicant also provides a tea withering device required for spreading treatment, by arranging a chain plate type conveying device on the upper inner side of the trough body, for placing tea leaves for withering treatment. When the tea withering treatment is completed, the tea leaves are conveyed to the conveyor belt by the chain plate type conveying device, and then conveyed to the next process by the conveyor belt, so as to solve the problem that the existing withering trough is inconvenient to transfer the tea leaves that have completed the withering treatment to the next process.

[0030] The improvements in the above two-step processes can effectively reduce the cost of dark tea making and have great promotion significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a top view of a tea withering device;

[0032] Figure 2 It is a left side view of the tea withering device;

[0033] Figure 3 It is a top view of the withering trough;

[0034] Figure 4 It is a structural schematic diagram of a tea leaf fixing device;

[0035] Figure 5 It is a structural schematic diagram of a steam fixing machine;

[0036] Figure 6 This is a schematic diagram of the installation of the tea scraping structure;

[0037] Figure 7 This is a schematic diagram of the installation of the aggregate trough;

[0038] Among them, marked in the attached drawings are: 1-1 withering trough, 2-1 trough body, 3-1 chain plate conveyor, 4-1 chain plate, 5-1 air permeable hole, 6-1 baffle, 7-1 conveyor belt; 1 hot air fixing machine, 2 steam fixing machine, 3 steam furnace, 4 first conveyor belt, 5 exhaust pipe, 6 steam pipe, 7 frame, 8 second conveyor belt, 9 trough body, 10 top cover, 11 discharge port, 12 discharge valve, 13 main pipe, 14 branch pipe, 15 third conveyor belt, 16 scraper, 17 support frame, 18 aggregate trough. DETAILED DESCRIPTION

[0039] In order to make the above-mentioned purpose, features and advantages of the present invention more obvious and easy to understand, the specific implementation of the present invention is described in detail below in conjunction with the examples. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific implementation disclosed below.

[0040] Embodiment 1:

[0041] A method for preparing Sanjiang Dong tea specifically comprises the following steps:

[0042] (1) Picking fresh leaves: Picking one bud, two or three leaves of summer and autumn tea leaves manually or by machine, picking is done between 8-11 am and 4-6 pm;

[0043] (2) Spreading: Place the picked fresh tea leaves in the tea withering device for spreading, with the thickness of the leaves not exceeding 30 cm;

[0044] like Figure 1-3 As shown, a tea withering device includes a withering trough 1-1, which includes a trough body 2-1 and a chain plate type conveyor 3-1 arranged at the upper inner part of the trough body 2-1. The chain plate type conveyor 3-1 has a plurality of chain plates 4-1 for placing tea leaves, and each of the chain plates 4-1 is provided with a plurality of ventilation holes 5-1.

[0045] The chain plate type conveyor 3-1 is a prior art, and specifically includes a driving motor, two chains, a driving shaft and a driven shaft. The driving shaft and the driven shaft are both rotatably mounted in the tank body 2-1. The driving shaft is provided with two driving sprockets, and the driven shaft is provided with two driven sprockets. One chain is installed on a driving sprocket and a driven sprocket on the same side, and the other chain is installed on another driving sprocket and another driven sprocket. The driving motor is fixedly mounted on the tank body 2-1 and connected to the driving shaft to drive the two chains to rotate. A plurality of chain plates 4-1 are sequentially mounted on the two chains and can rotate with the chains to realize material transmission.

[0046] Among them, the left and right ends of the chain plates of the chain-type conveyor 3-1 are hidden in the trough body 2-1. Correspondingly, the two chains and the corresponding sprockets are also hidden in the trough body 2-1 to avoid contact with operators and improve safety. The top surface of the chain-type conveyor 3-1 is provided with baffles 6-1 on the other three sides except the discharge end. The baffles 6-1 are movably connected to a number of chain plates 4-1 and are fixedly connected to the trough body 2-1 of the withering trough 1-1. The movable connection can be understood as: the bottom of the baffle is in contact with the top of the chain plate, and the chain plate 4-1 can move relative to the baffle 6-1. The three baffles 6-1 can confine the tea leaves on the chain-type conveyor 3-1 during the withering process.

[0047] The discharging end of the chain plate conveyor 3-1 is provided with a conveyor belt 7-1 for receiving tea leaves and conveying the tea leaves to the next process, and the conveying direction of the conveyor belt 7-1 is perpendicular to the conveying direction of the chain plate conveyor 3-1. In this embodiment, the conveyor belt 7-1 is a trough conveyor belt, which is convenient for conveying tea leaves.

[0048] A chain plate type conveyor 3-1 is provided on the upper inner side of the trough body 2-1 of the withering trough 1-1 to place tea leaves for withering treatment. Several chain plates 4-1 of the chain plate type conveyor 3-1 are provided with several ventilation holes 5-1. The entire conveying surface is equivalent to a mesh plate structure, which effectively dissipates the hot air generated by the hot air blower in the trough body 2-1 and accelerates the withering treatment of the tea leaves. When the withering treatment of the tea leaves is completed, the tea leaves are conveyed to the conveyor belt 7-1 by the chain plate type conveyor 3-1, and then conveyed to the next process by the conveyor belt 7-1, thereby improving the working efficiency of the operator and reducing the workload of the operator.

[0049] The number of withering troughs 1-1 is greater than two, and the number of conveyor belts 7-1 is one. In this embodiment, the number of withering troughs 1-1 is three. The equipment is provided with multiple withering troughs 1-1 sharing one conveyor belt 7-1, and tea leaves of multiple withering troughs 1-1 can be transferred by one conveyor belt 7-1, thereby reducing the number of conveyor belts 7-1, reducing equipment costs, and reducing the occupied area. In addition, a single conveyor belt 7-1 can better cooperate with the withering equipment of the next process.

[0050] In addition, a control switch is provided on the trough body 2-1 of the withering trough 1-1, and the control switch, the chain plate type conveyor device 3-1 and the conveyor belt 7-1 are all electrically connected to the controller. Among them, the controller is a PLC. A control switch is provided on the trough body 2-1 of the withering trough 1-1, which is convenient for the operator to operate. When the tea leaves need to be transferred, the operator starts the control switch, and the controller controls the corresponding chain plate type conveyor device 3-1 and the conveyor belt 7-1 to operate. After the set working time, the controller controls the chain plate type conveyor device 3-1 and the conveyor belt 7-1 to automatically stop working, and the tea transfer task is completed;

[0051] (3) Fixing: Use a fixing device to fix the tea leaves after spreading, and ensure that the fixing temperature is not too high or too low during the fixing process;

[0052] like Figure 4-5 As shown, a tea-tea-fixing device comprises a hot air tea-fixing machine 1, a steam tea-fixing machine 2 and a steam oven 3, wherein the steam oven 3 is connected to the steam chamber of the steam tea-fixing machine 2 via a steam pipe 6.

[0053] The discharge end of the hot air fixing machine 1 is connected to the feed end of the steam fixing machine 2 through the first conveyor belt 4 , and the exhaust port of the hot air fixing machine 1 is connected to the steam chamber of the steam fixing machine 2 through the exhaust pipe 5 .

[0054] Among them, the steam fixing machine 2 includes a frame 7 and a second conveyor belt 8, a steam chamber is arranged on the frame 7, and the second conveyor belt 8 is horizontally arranged on the frame 7 and penetrates the steam chamber. The steam chamber includes a tank body 9 and a top cover 10, the tank body 9 is arranged on the frame 7, and its top and left and right sides are both open structures, the top cover 10 covers the top of the tank body 9, and the top of the top cover 10 is provided with a discharge port 11. The top cover 10 is detachably connected to the tank body 9, and the discharge port 11 is provided with a discharge valve 12, which can adjust the flow rate of the discharge port 11. In this embodiment, the top cover 10 is a flip cover, one side of which is hinged on the frame 7, and the other side is connected to the frame 7 by a lock. When the steam fixing machine 2 needs to be repaired or other operations are performed, the top cover 10 can be opened.

[0055] The bottom of the tank body 9 is connected to the exhaust pipe 5 and the steam pipe 6 through a mixing pipe assembly. The mixing pipe assembly includes a main pipe 13 and at least two branch pipes 14. The main pipe 13 is connected to the tank body 9 through at least two branch pipes 14, and the middle of the main pipe 13 is connected to the exhaust pipe 5 and the steam pipe 6. In this embodiment, four branch pipes 14 are provided, which are evenly distributed at the bottom of the tank body 9. The hot air transmitted by the exhaust pipe 5 and the steam transmitted by the steam pipe 6 are fully mixed in the mixing pipe assembly and then introduced into the steam chamber for steam sterilization.

[0056] By combining the hot air fixing machine 1 with the steam fixing machine 2, the tea leaves are fixed with hot air and then steam fixed. On the one hand, the working temperature of the hot air fixing machine 1 can be reduced to avoid the phenomenon of scorched leaves and scorched edges during the tea fixing process. On the other hand, steam fixing is beneficial to deactivate the activity of enzymes and inhibit enzymatic oxidation. The combination of the two also shortens the steam fixing time and can avoid the problem of excessive water content of tea leaves.

[0057] In addition, hot air fixation and steam fixation are carried out separately, which is conducive to controlling and adjusting the fixation temperature to avoid the fixation temperature being too high or too low. For example, the working temperature of the hot air fixation machine 1 can be set to 260-280°C, and the working temperature of the steam fixation machine 2 can be set to 200-240°C. The two do not interfere with each other, ensuring the stability and effectiveness of the working temperature.

[0058] By transmitting the hot air discharged from the hot air withering machine 1 to the steam withering machine 2, on the one hand, the hot air is reused to improve energy utilization, and on the other hand, the dry hot air is mixed with the steam to reduce the humidity of the steam to a certain extent, further reducing the water content of the tea leaves during steam withering.

[0059] The tea-tea-fixing device comprises a hot air fixing machine, a steam fixing machine and a steam furnace, wherein the steam furnace is connected to a steam chamber of the steam fixing machine through a steam pipe, the discharge end of the hot air fixing machine is connected to a feed end of the steam fixing machine through a first conveyor belt, and the exhaust port of the hot air fixing machine is connected to the steam chamber of the steam fixing machine through an exhaust pipe; the temperature of the hot air fixing machine is controlled at 260-280° C., and the temperature of the steam fixing machine is controlled at 200-240° C.;

[0060] like Figure 6 As shown, the steam fixing machine 2 also includes a tea scraping structure, which is arranged at the lower part of the discharge end of the second conveyor belt 8, and includes a scraper 16 and a support frame 17. The top of the scraper 16 is movably connected to the belt of the second conveyor belt 8, and the bottom of the scraper 16 is connected to the frame 7 through the support frame 17. A third conveyor belt 15 is arranged below the tea scraping structure, and the first conveyor belt 4 and the third conveyor belt 15 are both climbing conveyor belts.

[0061] The discharge end of the steam withering machine 2 is provided with a tea scraping structure, through which the scraper 16 of the tea scraping structure scrapes off the tea leaves stuck on the second conveyor belt 8, so that the tea leaves can be better conveyed to the next process, avoiding the inconvenience caused by manual cleaning of the tea leaves.

[0062] like Figure 7 As shown, a collecting trough 18 is provided at the discharge end of the second conveyor belt 8, and the collecting trough 18 is installed on the frame 7 and is located below the scraper 16. The tea leaves falling from the second conveyor belt 8 are collected by the collecting trough 18 and directed to the third conveyor belt 15. The side of the collecting trough 18 facing the second conveyor belt 8 is wider so that the tea leaves can enter smoothly, and the side of the collecting trough 18 facing the third conveyor belt 15 is smaller so that the width of the third conveyor belt 15 can be smaller.

[0063] Through the research of the applicant, it is found that the conventional hot air fixing machine 1 and the steam fixing machine 2 can be integrated to give full play to the fixing advantages of each of them and make full use of the existing resources of the enterprise. Only a simple modification of the existing fixing equipment is required to avoid the problem of waste of resources and reduce the cost of purchasing equipment for the enterprise.

[0064] (4) Preliminary twisting: After withering, the tea leaves are twisted while still hot to form strips; the twisting is performed by light pressing and the twisting time is 25 minutes;

[0065] (5) Piling: The height of the pile shall not exceed 1m, and the pile shall be placed in a dark pile-making room with the temperature controlled at 35°C and the humidity controlled at 85%. The time of the pile-making is 12 hours;

[0066] (6) re-kneading the tea leaves after the fermentation;

[0067] (7) Drying: Place the tea leaves after re-kneading in an environment with a temperature of 40°C and a humidity of 30% to dry until the moisture content of the tea leaves is less than 9.0%.

[0068] Embodiment 2:

[0069] The method is basically the same as Example 1, except that: Step (4) initial twisting: after withering, the tea leaves are rolled while hot to initially roll them into strips; the rolling is performed by light pressing and the rolling time is 20 minutes; (5) pile fermentation: the pile fermentation height does not exceed 1 meter, and the pile fermentation is carried out in a dark pile fermentation room with the temperature controlled at 30°C and the humidity at 80%; the pile fermentation time is 8 hours.

[0070] Embodiment 3:

[0071] The method is basically the same as Example 1, except that: Step (4) initial twisting: after withering, the tea leaves are rolled while hot to initially roll them into strips; the rolling is performed by light pressing and the rolling time is 30 minutes; (5) pile fermentation: the pile fermentation height does not exceed 1 meter, and the pile fermentation is carried out in a dark pile fermentation room with the temperature controlled at 45°C and the humidity at 90%; the pile fermentation time is 16 hours.

[0072] Comparative Example 1:

[0073] The basic preparation steps are the same as those in Example 1, except that the green-fixing device used in the green-fixing step is a Jingcheng 6CZ-200 green-fixing machine purchased from the market.

[0074] Comparative Example 2:

[0075] The basic preparation steps are the same as those in Example 1, except that the green-fixing device used in the green-fixing step is a 6CZQRC-500 green-fixing machine purchased from the market.

[0076] Comparative Example 3:

[0077] The basic preparation steps are the same as those in Example 1, except that the withering device used in the spreading step does not use the withering device improved and researched by the applicant, but directly uses a conventional rectangular withering trough. When the tea leaves are withered, they are manually collected for transfer to the next process.

[0078] 1. Sensory quality and scoring

[0079] The Sanjiang Dong tea (dark tea) prepared according to Examples 1-3 and the Sanjiang Dong tea (dark tea) prepared according to Comparative Examples 1-3 were compared as follows. The specific sensory qualities and scores are shown in Tables 1 and 2 below, respectively.

[0080] Sensory evaluation: GB / T23776—2018 Sensory evaluation method for tea.

[0081] Scoring: The sensory evaluation method is to select 10 experienced dark tea professionals to form a scoring panel to evaluate and score the product's appearance, soup color, aroma, taste and leaf bottom, and take the average value as the final score.

[0082] Table 1 Sensory quality comparison table

[0083]

[0084] From the data in Table 1, it can be seen that the quality of Sanjiang Dong tea obtained by the preparation scheme of this team is much better than that of Comparative Examples 1, 2 and 3, and the sensory qualities of Comparative Examples 1, 2 and 3 are equivalent.

[0085] Table 2 Comparison of sensory quality scores

[0086]

[0087] From Table 2, after sensory scoring, the scores given by 10 tea tasters show that the total score of Sanjiang Dong tea prepared by the scheme of the present invention is much higher than that of comparative examples 1, 2, and 3, but the score difference between comparative documents 1, 2, and 3 is also large. This shows that the use of the process scheme of the present application can effectively improve the sensory quality and sensory score of Sanjiang Dong tea.

[0088] 2. Determination of tea ingredients

[0089] The Sanjiang Dong tea prepared by the process of Examples 1-3 and Comparative Examples 1-3 was tested for the following components, and the specific test data are shown in Table 3.

[0090] The determination of tea polyphenols in tea leaves shall refer to GB / T 8313-2008.

[0091] The determination of total free amino acids in tea shall refer to GB / T 8314-2013.

[0092] The determination method of caffeine in tea refers to GB / T 8312-2002.

[0093] Detection of γ-aminobutyric acid by high performance liquid chromatography.

[0094] Soluble sugars were determined by anthrone colorimetry.

[0095] Table 3 Ingredient comparison table

[0096]

[0097] From the data in Table 3, it can be seen that the contents of tea polyphenols, total free amino acids, caffeine, γ-aminobutyric acid and soluble sugar in the Sanjiang Dong tea prepared by the technical solution of the present application are significantly improved; this shows that the improvement of the withering process can effectively increase the content of the above-mentioned components, and the withering treatment process also has a certain influence on the later process steps. The improvement of these components can effectively improve the taste, aroma and soup color.

[0098] The present invention is not limited to the above-mentioned specific embodiments, but extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

Claims

1. A method for preparing Sanjiang Dong tea, characterized in that: The specific steps include the following: (1) Picking fresh leaves: Picking one bud, two or three leaves of summer and autumn tea leaves manually or by machine, picking is done between 8-11 am and 4-6 pm; (2) Spreading: Place the picked fresh tea leaves in the tea withering device for spreading, with the thickness of the leaves not exceeding 30 cm; The tea withering device comprises a withering trough, which comprises a trough body and a chain plate type conveyor device arranged at the upper inner side of the trough body; the chain plate type conveyor device comprises a plurality of chain plates for placing tea leaves, each of which is provided with a plurality of ventilation holes; a conveyor belt for receiving tea leaves and conveying the tea leaves to the next process is arranged at the discharge end of the chain plate type conveyor device; (3) Fixing: Use a fixing device to fix the tea leaves after spreading, and ensure that the fixing temperature is not too high or too low during the fixing process; The tea-tea-fixing device comprises a hot air fixing machine, a steam fixing machine and a steam furnace, wherein the steam furnace is connected to a steam chamber of the steam fixing machine through a steam pipe, the discharge end of the hot air fixing machine is connected to a feed end of the steam fixing machine through a first conveyor belt, and the exhaust port of the hot air fixing machine is connected to the steam chamber of the steam fixing machine through an exhaust pipe; the temperature of the hot air fixing machine is controlled at 260-280° C., and the temperature of the steam fixing machine is controlled at 200-240° C.; (4) Preliminary twisting: After withering, the tea leaves are twisted while still hot to form strips; the twisting is performed by light pressing and the twisting time is 20-30 minutes; (5) Piling: The height of the pile shall not exceed 1m, and the pile shall be placed in a dark pile-making room with a temperature of 30-45°C and a humidity of 80%-90%. The time of the pile-making is 8-16 hours. (6) re-kneading the tea leaves after the fermentation; (7) Drying: Place the tea leaves after re-kneading in an environment with a temperature of 40°C and a humidity of 30% to dry until the moisture content of the tea leaves is less than 9.0%.

2. The method for preparing Sanjiang Dong tea according to claim 1, characterized in that: The left and right ends of the chain plates of the chain-plate conveyor device are hidden in the trough body; the top surface of the chain-plate conveyor device is provided with baffles on the other three sides except the discharge end, and the baffles are movably connected to a plurality of chain plates and fixedly connected to the trough body of the withering trough.

3. The method for preparing Sanjiang Dong tea according to claim 1, characterized in that: A control switch is provided on the trough body of the withering trough, and the control switch, the chain plate type conveying device and the conveyor belt are all electrically connected to the controller, and the controller is a PLC.

4. The method for preparing Sanjiang Dong tea according to claim 1, characterized in that: The conveying direction of the conveyor belt is arranged perpendicularly to the conveying direction of the chain plate conveyor device; the number of the withering troughs is greater than two, and the number of the conveyor belt is one.

5. The method for preparing Sanjiang Dong tea according to claim 1, characterized in that: The steam fixing machine includes a frame and a second conveyor belt, the steam chamber is arranged on the frame, and the second conveyor belt is horizontally arranged on the frame and passes through the steam chamber; the steam chamber includes a trough body and a top cover, the trough body is arranged on the frame, and its top and left and right sides are both open structures, the top cover is closed on the top of the trough body, and a discharge port is arranged on the top of the top cover.

6. The method for preparing Sanjiang Dong tea according to claim 5, characterized in that: The top cover is detachably connected to the tank body, and the discharge port is provided with a discharge valve; the bottom of the tank body is connected to the exhaust pipe and the steam pipe through a mixing pipe assembly.

7. The method for preparing Sanjiang Dong tea according to claim 6, characterized in that: The mixing tube assembly comprises a main tube and at least two branch tubes, the main tube is connected to the tank body through at least two branch tubes, and the middle part of the main tube is connected to the exhaust pipe and the steam pipe; a third conveyor belt is arranged below the tea scraping structure.

8. The method for preparing Sanjiang Dong tea according to claim 7, characterized in that: The first conveyor belt and the third conveyor belt are both climbing conveyor belts.

9. The method for preparing Sanjiang Dong tea according to claim 7, characterized in that: The discharging end of the second conveyor belt is provided with a collecting trough, which is installed on the frame and located below the scraper.

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