Automatic processing system and method for secondary fermentation of tea leaves

Abstract

The invention relates to the technical field of tea leaf processing, discloses an automatic processing system and method for secondary fermentation of tea leaves, and aims to solve the problems of sensing lag, weak regulation and control capability, unintelligent pile turning and the like in the secondary fermentation process. The system is composed of a pretreatment module, a metering water transfer module, a program-controlled fermentation module, an extrusion forming module, a drying stir-frying module and a central control system. According to the program-controlled fermentation module disclosed by the invention, a multi-dimensional sensing detection matrix is utilized to go deep into a pile body to monitor temperature, humidity and gas components in real time, and a self-adaptive flexible pile turning mechanism executes accurate turning action based on microbial metabolism feedback; and the central control system realizes full-flow streamlined closed-loop regulation and control. According to the invention, high-precision perception and intelligent intervention of the fermentation environment are realized, the quality consistency of tea leaves is guaranteed, the sensory quality and the production efficiency are improved, and the labor dependence and the food hygiene risk are reduced.

Description

Technical Field

[0001] This invention relates to the field of tea processing technology, and in particular to an automated processing system and method for secondary fermentation of tea. Background Technology

[0002] In the tea processing industry, secondary fermentation is a core and crucial process that determines the quality of specific tea types such as dark tea, Pu'er tea, and Fu brick tea. By inducing microbial metabolism and endogenous enzymatic oxidation reactions under specific temperature and humidity conditions, profound biochemical transformations occur in the tea leaves' internal substances, such as tea polyphenols, amino acids, and polysaccharides, resulting in the unique aged aroma, mellow flavor, and health-promoting metabolites. In traditional production models, the secondary fermentation process heavily relies on experienced craftsmen for manual control, using sensory judgment to determine the timing of turning the pile, the water ratio, and the fermentation progress. However, with the expansion of the industry, the limitations of manual control have become increasingly apparent. Not only is production efficiency extremely low, but it is also highly susceptible to the subjective experience of operators, leading to batch-to-batch fluctuations in product quality. More importantly, due to the long fermentation cycle and large pile size, manual operation makes it difficult to achieve precise real-time monitoring of the internal microenvironment of the pile, easily causing hygiene risks and uneven fermentation problems. Furthermore, the rigid stirring of existing equipment can damage the tea leaf tissue.

[0003] To address these issues, a series of automated fermentation devices have emerged in the industry, aiming to replace manual operation with mechanization. For example, one existing technology utilizes a rotating fermentation tank combined with stirring blades and atomizing nozzles, designed to improve fermentation uniformity through rotation, turning, and automatic humidification. Another approach attempts to employ an inclined aeration tank and a three-dimensional circulating air duct structure, along with a non-rigid turning mechanism, to reduce physical damage to the tea leaves. These technologies have, to some extent, improved the operational intensity of large-scale production and achieved preliminary automated recording of environmental parameters. However, in practical industrial applications, existing automated solutions have revealed several technical problems when dealing with the unique biophysical characteristics of secondary fermentation.

[0004] Secondary fermentation is not a static physical heating or humidification process, but a dynamic autothermal biochemical process driven by microbial community succession. Current technologies often treat the fermentation pile as a homogeneous physical object at the principle level, neglecting the extreme sensitivity of microorganisms to the microenvironment at different metabolic stages. Specifically, in the later stages of fermentation, dominant microbial communities, such as *Aspergillus cristatus*, exhibit extremely vigorous metabolism, and the respiration heat they generate leads to a huge temperature gradient in the center of the pile. Existing equipment often only has macroscopic environmental temperature and humidity sensing capabilities, lacking real-time feedback on the state deep within the pile core. This prevents the system from dynamically adjusting to local "hot spots," easily causing localized overheating and "pile burning," disrupting the directional succession of the dominant microbial community.

[0005] Furthermore, there is a significant logical disconnect between the existing turning mechanism and the requirements of the fermentation process. Different stages of secondary fermentation (such as the early enzymatic oxidation stage and the later microbial-dominated stage) have vastly different tolerances to oxygen flux, moisture distribution, and physical stress. Existing stirring mechanisms typically employ fixed frequencies and intensities, inevitably causing mechanical breakage of tea leaves while attempting to replenish oxygen and cool the tea through forced stirring. This physical damage not only impairs the appearance of the tea but also leads to uncontrolled oxidation of beneficial internal substances before their transformation due to premature destruction of cell structure, severely affecting the aroma accumulation and flavor profile of the finished tea.

[0006] Secondly, existing automated systems suffer from a lack of coordination across the entire process. Improving the quality of secondary fermentation involves a complete chain of processes, from sieving and removing impurities from the dry tea leaves and precisely adjusting the water content to post-fermentation shaping and drying. Existing technologies often focus on a single fermentation stage, lacking closed-loop control capabilities from raw material pretreatment to finished product processing. For example, in the automatic water adjustment stage, failure to accurately measure and replenish water based on the real-time moisture content of the tea leaves directly impacts the activity of microorganisms in the subsequent fermentation chamber. Furthermore, during the post-fermentation transfer, extrusion shaping, and drying processes, a lack of programmable logic linked to the fermentation status can easily lead to the loss of fermentation results due to heat damage or physical pressure. Due to the lack of multi-dimensional sensing, microbial metabolic feedback, and end-to-end adaptation, existing technologies struggle to effectively increase the content of extractable substances and the accumulation of flavor compounds while ensuring consistent tea quality.

[0007] In summary, existing tea fermentation systems, when faced with the complex process of secondary fermentation, exhibit several technical problems, including lagging perception of the internal state of the fermentation pile, insufficient ability to coordinate and control multiple environmental parameters, a lack of intelligent adaptability in the turning strategy, and a loosely structured process throughout the entire process. Therefore, constructing an automated processing system capable of real-time perception of microbial metabolic needs, high-precision moisture measurement, and maintaining the balance of the fermentation microenvironment through flexible adaptive mechanisms has become a key challenge for achieving large-scale, standardized production in the current tea deep processing field. Summary of the Invention

[0008] To address the aforementioned issues, this invention aims to provide an automated processing system and method for secondary fermentation of tea, thereby achieving precision, intelligence, and standardization throughout the entire secondary fermentation process. This will improve the sensory quality and leaching rate of tea's internal substances while ensuring the consistency of tea quality.

[0009] To achieve the above objectives, the technical solution of the present invention is as follows:

[0010] On one hand, the present invention provides an automated processing system for secondary fermentation of tea leaves, which consists of a dry tea raw material pretreatment module, an automatic metering and water adjustment and conveying module, a programmable secondary fermentation module, an automatic extrusion molding module, a continuous drying and frying module, and an integrated central control system.

[0011] The pre-processing module for dried tea raw materials includes a vibrating sieve, a cutting and leveling machine, a multi-stage shaking sieve, a magnetic separator, and a visual color sorter connected in sequence. The vibrating sieve has three layers of screens with different apertures: the top layer has an aperture of 12mm to 15mm to remove large foreign objects; the middle layer has an aperture of 4mm to 6mm to collect tea leaves that meet specifications; and the bottom layer has an aperture of 0.5mm to remove fine fragments. The cutting and leveling machine is located below the discharge port of the vibrating sieve and is equipped with an adjustable-gap rotating blade assembly to cut tea leaves exceeding a preset size to a uniform specification. The multi-stage shaking sieve is driven by an eccentric shaft to achieve reciprocating shaking, with a vibration frequency of 10Hz to 25Hz, further grading the cut tea leaves. The magnetic separator includes a set of rare-earth permanent magnet rods with a magnetic induction intensity of over 12,000 gauss. These rods are arranged in an alternating pattern within the conveying channel to adsorb ferromagnetic impurities from the tea leaves. The visual color sorter is equipped with a full-color CCD sensor and a near-infrared sensor. It uses a high-speed electromagnetic spray valve to remove non-tea impurities and discolored leaves from the tea leaves; the response delay of the electromagnetic spray valve is less than 1 ms.

[0012] The automatic metering and conveying module includes a real-time dry tea weighing mechanism, a non-contact moisture detector, a high-precision atomizing humidification component, and a spiral mixing conveyor. The real-time dry tea weighing mechanism uses a high-precision pressure sensor, achieving a static metering accuracy of 0.1%. The non-contact moisture detector, based on near-infrared spectral absorption, is installed above the feed hopper of the spiral mixing conveyor to obtain the initial moisture content of the tea leaves to be fermented in real time. The high-precision atomizing humidification component includes an electromagnetic flowmeter, a variable frequency water pump, and a set of ultrasonic atomizing nozzles arranged on the inner wall of the spiral mixing conveyor. The droplet diameter generated by the ultrasonic atomizing nozzles is less than 50 μm. The central control system adjusts the speed of the variable frequency water pump and the opening of the electromagnetic flowmeter in real time based on the difference between the initial moisture content and the preset target moisture content, achieving closed-loop control of the tea leaf water replenishment. The blades of the spiral mixing conveyor are coated with a polytetrafluoroethylene (PTFE) anti-stick coating to prevent the tea leaves from agglomerating or sticking together during the water adjustment process.

[0013] The programmable secondary fermentation module is the core of the entire system, comprising several independently controlled insulated fermentation tanks. Each fermentation tank consists of a double-layered stainless steel insulated body, a multi-dimensional sensing matrix, an adaptive flexible turning mechanism, and a microenvironment adjustment unit. The inner wall of the double-layered stainless steel insulated body is made of SUS316L acid and alkali resistant stainless steel, with a 50mm thick rigid polyurethane foam filling in the middle layer. The multi-dimensional sensing matrix includes an array of several sets of insertable probes. Each probe has three sets of platinum resistance temperature sensors (PT100), one set of capacitive moisture sensors, and one set of gas sampling holes arranged at equal intervals in the vertical direction. The gas sampling holes are connected to a gas analyzer outside the tank via pipelines to detect the concentrations of oxygen, carbon dioxide, and volatile metabolites such as ammonia and ethanol inside the fermentation tank.

[0014] The adaptive flexible turning mechanism is installed on a three-axis gantry frame on the upper part of the fermentation tank, including a Z-axis lifting drive, a rotary drive, and a flexible turning hand. The flexible turning hand is made of food-grade silicone. The central control system controls the flexible turning hand to insert, turn, and scatter at specific spatial coordinate points based on the temperature gradient and gas concentration changes inside the pile obtained by the multi-dimensional sensor detection matrix. When the temperature difference between the core and the surface of the pile exceeds a preset threshold of 5°C, or when the carbon dioxide concentration exceeds a preset value of 3%, the adaptive flexible turning mechanism is automatically triggered. Through flexible turning, it achieves heat dissipation, gas exhaust, and oxygenation of the pile, while avoiding damage to the tea tissue due to excessive mechanical shearing force.

[0015] The microenvironment control unit includes an ultrasonic humidifier, an electric heating array, a cooling coil, and a variable frequency circulating fan. The variable frequency circulating fan is connected to a high-efficiency air filter through a ventilation duct installed on the side wall of the enclosure, realizing the circulation and purification of airflow within the enclosure. The central control system controls the temperature, humidity, and oxygen concentration within the enclosure through PID control logic.

[0016] The automatic extrusion molding module connects to the discharge port of the programmable secondary fermentation module via an automated conveyor belt, and includes a quantitative dispensing machine and a hydraulic molding machine. The quantitative dispensing machine uses volumetric or gravimetric metering to distribute the fermented and softened tea leaves into specific molds. The hydraulic molding machine is equipped with a pressure displacement monitoring system, which adjusts the output pressure (5MPa to 20MPa) and holding time of the hydraulic cylinder to press the tea leaves into a preset shape. The mold surface has permeable micropores to facilitate moisture migration during the subsequent drying process.

[0017] The continuous drying and roasting module includes a chain dryer and a drum dryer. The chain dryer is divided into several independently temperature-controlled roasting sections, using an air-source heat pump as the heat source, with the drying air velocity controlled between 0.5 m / s and 2.0 m / s. The drum dryer is located at the end of the dryer, providing radiant heat through infrared heating tubes to further transform the aroma substances on the surface of the tea leaves.

[0018] Based on the above system, the present invention also provides an automated processing method for secondary fermentation of tea, specifically including the following steps:

[0019] Step S1: Pre-treatment and impurity removal of dried tea raw materials. First, the dried tea raw materials to be processed are fed into a vibrating sieve machine, where they are physically graded through three layers of sieves with different apertures to remove large impurities, non-standard tea pieces, and fine dust. The graded tea pieces are then cut to a fixed length by a uniform cutter to ensure the uniformity of the raw material size. Subsequently, a multi-stage vibrating sieve machine is used for a second screening, followed by a magnetic separator to adsorb iron impurities. Finally, a visual color sorter uses CCD and near-infrared sensors to scan each tea leaf. Based on preset color and spectral characteristics, high-pressure airflow removes spoiled leaves, tea stems, and other foreign matter, resulting in high-purity dried tea raw materials.

[0020] Step S2: Automatic metering and water adjustment, material feeding, and intelligent fermentation control. S201: Raw material metering and initial state sensing. Pre-treated dry tea leaves are dynamically weighed using a belt scale, while a near-infrared moisture detector installed above the conveyor line measures the initial moisture content of the dry tea in real time. S202: Precise closed-loop water adjustment. The central control system calculates the required water replenishment based on the measured initial moisture content and the set target fermentation moisture content (typically 25% to 32%). A variable frequency water pump controls the flow rate of the ultrasonic atomizing nozzles, and under the powerful stirring of a spiral mixing conveyor, the atomized water is evenly sprayed onto the surface of the tea leaves, ensuring uniform moisture penetration from the leaf surface to the interior. S203: Automatic packaging and environmental initialization. The water-adjusted tea leaves are automatically conveyed into a dedicated programmable fermentation chamber. The central control system activates the microenvironment adjustment unit, setting the initial temperature inside the chamber to 35℃ to 45℃ and the relative humidity to above 85%, creating conditions for the initial colonization of microorganisms and the recovery of endogenous enzyme activity. S204: Dynamic monitoring and microbial metabolic feedback driven. During fermentation, a multi-dimensional sensor matrix acquires real-time data on temperature, moisture, and gas composition at different depths within the fermentation pile. When the system detects that the temperature at the center of the pile is rising due to microbial respiration and approaching the upper threshold (e.g., 60°C to 65°C), the central control system automatically increases the frequency of the variable frequency circulating fan and controls the adaptive flexible turning mechanism to precisely turn the area. When the gas analyzer shows an increase in carbon dioxide concentration and a decrease in oxygen concentration below 5%, the system opens the fresh air valve and coordinates with the turning action to increase the porosity of the pile, induce the metabolism of beneficial aerobic bacteria (such as Aspergillus cristatus), and simultaneously inhibit the growth of anaerobic bacteria and the generation of off-odors. Through this dynamic regulation based on microbial metabolic feedback, the system maintains homeostasis within the pile, guides the dominant bacterial community to undergo directional succession, and promotes the deep oxidation of tea polyphenols, the conversion of proteins into amino acids, and the accumulation of volatile aroma substances.

[0021] Step S3: Fermentation Completion Determination and Automatic Extrusion Molding. When the concentration of volatile metabolites within the fermentation chamber reaches the preset characteristic fingerprint spectrum, and the tea moisture content and sensory color meet the standards as determined by an online camera, the central control system instructs the fermentation chamber to automatically discharge the tea. The softened tea leaves are then conveyed to the automatic extrusion molding module. After precise weighing and packaging by the quantitative packaging machine, the hydraulic molding machine performs flexible extrusion according to a preset pressure curve. During extrusion, the pressure increases slowly from low to high to avoid excessive breakage of the tea cell walls due to instantaneous high pressure, thus preserving more of the internal effective components.

[0022] Step S4: Programmed Drying and Aroma Enhancement. The shaped tea leaves enter a continuous drying and frying module. First, they undergo a gradient cooling drying process in a chain dryer: initially, a low temperature (50℃ to 60℃) and high airflow remove surface moisture; in the middle stage, a medium temperature (70℃ to 80℃) promotes internal moisture migration; and in the later stage, a high temperature (above 90℃) fixes the quality and deactivates residual enzyme activity. Finally, in a drum dryer, a "fragrance enhancement" treatment is performed using instantaneous high temperature (120℃ to 140℃), causing the sugar-amine complexes within the tea leaves to undergo the Maillard reaction, forming a unique aged aroma and mellow flavor.

[0023] The automated processing system and method for secondary fermentation of tea provided by this invention has the following beneficial effects:

[0024] 1. This invention achieves high-precision three-dimensional sensing and control of the fermentation microenvironment. Compared to traditional technologies that rely solely on monitoring environmental temperature and humidity, this invention uses a multi-dimensional sensing matrix to penetrate deep into the fermentation pile, directly acquiring the core's biological metabolic information (such as temperature gradient and gas composition). This closed-loop control mechanism based on microbial metabolic feedback effectively eliminates "hot spots" and "dead zones" within the fermentation pile, ensuring the consistency of the fermentation process and fundamentally preventing quality defects such as localized burning or incomplete fermentation.

[0025] 2. This invention resolves the conflict between physical damage to tea leaves and fermentation efficiency in automated production through an adaptive flexible turning mechanism. The flexible silicone turning hand, combined with high-precision three-axis motion control, simulates the gentle movements of manual turning, achieving efficient heat dissipation, oxygen replenishment, and moisture redistribution without damaging the integrity of the leaves. This not only maintains the good appearance of the finished tea leaves but also, by protecting the leaf tissue structure, makes the biotransformation process more controlled.

[0026] 3. The fully automated closed-loop control of this invention improves resource utilization and product quality, realizing streamlined operations from raw tea leaves to finished tea. In particular, the precise automatic water adjustment system and the gradient drying process in the later stages of fermentation maximize the extraction of the tea's inherent substances without altering its intrinsic characteristics. Experimental results show that tea processed by this system, compared to traditional automated processes, exhibits improved body and aroma persistence, and its water-soluble extract content increases by approximately 2.5%, thereby enhancing the product's economic added value.

[0027] 4. This invention reduces food hygiene risks. The fully enclosed, stainless steel fermentation environment and integrated air purification system effectively isolate external sources of contamination. Through online monitoring of carbon dioxide and volatile organic compounds, the system can automatically identify and inhibit the growth of unwanted microorganisms, ensuring the microbial ecological stability of the fermentation process and making the finished tea fully meet the high standards of modern food safety.

[0028] 5. This invention possesses excellent process adaptability and a high level of intelligence. The central control system can store expert process curves for different types of tea (such as Pu'er, Fu brick, and black tea). By simply switching control parameters, the system can automatically adapt to the personalized requirements of different stages for temperature, humidity, turning frequency, and drying intensity, realizing a flexible "one machine, multiple functions" production mode, reducing reliance on highly skilled human experience, and improving production efficiency and quality stability.

[0029] In summary, this invention integrates mechanical, electronic, sensing, and biochemical processes to construct a complete intelligent production model for the secondary fermentation of tea. It not only overcomes the shortcomings of existing technologies in terms of pile sensing, environmental control, and physical protection, but also improves tea quality through synergistic optimization of the entire process, providing technical support for the large-scale, standardized, and high-end development of the tea processing industry.

[0030] Furthermore, in a preferred embodiment of the present invention, each probe in the multi-dimensional sensing matrix adopts a retractable structure. Before the adaptive flexible turning mechanism is about to perform an action in a certain area, the probe in that area retracts upward into the top of the container under the action of the pneumatic actuator to avoid mechanical collision between the turning hand and the probe. After the turning action is completed, the probe is inserted downward into the pile body to a predetermined depth to continue performing the sensing task. This mechanical coordination mechanism ensures that real-time monitoring and physical intervention can proceed in parallel.

[0031] Furthermore, in a preferred embodiment of the present invention, the high-precision atomizing humidification component also includes a nutrient solution addition unit. During the secondary fermentation of a specific type of tea (such as Fu brick tea), the central control system can control the metering pump to add a specific proportion of microbial inducer or nutrient substrate to the replenishing water. The microbial inducer is a mixture of tea polyphenol oxidation products at a mass fraction of 0.1%–0.5%, or a gallic acid solution at 0.05%–0.2%; its addition amount is calculated at 0.3%–0.8% of the dry tea weight, and is used to promote the germination of Aspergillus cristatus spores. The nutrient solution is fully atomized by ultrasound and uniformly combined with the tea leaves, thereby precisely controlling the inoculation amount and initial growth rate of the target microorganism (such as Aspergillus oryzae).

[0032] Furthermore, as a preferred embodiment of the present invention, the integrated central control system has a data traceability function. The system records all sensor data, actuator action logs, and environmental parameter curves for each batch, each fermentation chamber, and each moment in real time via industrial Ethernet. This data is stored on a local server or in a cloud database using encryption algorithms, forming a complete digital twin archive of production data, providing a data foundation for product quality traceability and subsequent process improvement.

[0033] Furthermore, in a preferred embodiment of the present invention, an electronic weighing module is installed at the bottom of the chamber of the programmable secondary fermentation module to monitor in real time the changes in the total mass of the pile due to water evaporation and microbial respiration during the fermentation process. The central control system combines local data from the moisture sensor with global data from the weighing module, and further improves the accuracy of water replenishment adjustment and discharge timing determination through dual verification logic.

[0034] Furthermore, in a preferred embodiment of the present invention, a temperature sensing element is embedded inside the mold of the automatic extrusion molding module to monitor the temperature change of the tea leaves in real time during the pressing process. If the mechanical heat generated by the extrusion causes the temperature to exceed a set safety threshold (e.g., 40°C), the system will automatically reduce the extrusion speed or open the cooling channels inside the mold to prevent thermal degradation of the tea leaves during the molding stage.

[0035] Furthermore, in a preferred embodiment of the present invention, the continuous drying and roasting module is equipped with a waste heat recovery device. A heat pump system is used to recover the sensible and latent heat of the hot, humid air discharged from the dryer, which is then used to preheat the incoming fresh air. This design ensures drying efficiency while reducing the overall system energy consumption, achieving a green and energy-saving processing flow.

[0036] Furthermore, in a preferred embodiment of the present invention, the visual color sorter in the dry tea raw material pretreatment module also integrates a leaf integrity assessment algorithm module. A high-speed image processor analyzes the outline integrity of the tea leaves and feeds the statistical data back to the central control system in real time. If an abnormally high breakage rate is detected, the system automatically adjusts the blade speed of the front-end cutting machine or the conveying frequency of the rear-end conveying mechanism to control the consistency of the raw materials from the source.

[0037] Furthermore, as a preferred embodiment of the present invention, the spiral mixing conveyor in the automatic metering and conveying module adopts a dual-shaft structure. The two spiral shafts operate in opposite directions and asynchronously. Through the alternating action of the generated shear stress and compressive stress, the atomized water can penetrate deeply into the micropores of the tea leaves, improving the microscopic uniformity of water distribution and laying the foundation for the uniform growth of subsequent microorganisms.

[0038] Furthermore, as a preferred embodiment of the present invention, the microenvironmental regulation unit of the programmable secondary fermentation module is also equipped with an ozone sterilization module. After each batch of fermentation is completed, the central control system automatically starts the sterilization program, using high-concentration ozone to thoroughly disinfect the internal space of the chamber and the ventilation ducts, preventing cross-contamination of microorganisms between different batches and ensuring absolute hygiene of the production environment.

[0039] Furthermore, in a preferred embodiment of the present invention, the conveying mechanism between the automatic extrusion molding module and the continuous drying and roasting module is equipped with an infrared preheater. Before the tea leaves enter the dryer, the infrared preheater rapidly heats the surface of the tea leaves, reducing the temperature difference between the inside and outside, thereby effectively preventing internal cracks or uneven color due to excessive surface water loss during the formal drying stage.

[0040] The processing system of this invention fully considers the special characteristics of the fermentation environment in its material selection. All metal parts in contact with tea leaves are made of 316L or 304 stainless steel that meets food safety standards, and the surface roughness Ra value is less than 0.4μm to reduce tea stain accumulation and bacterial growth. All non-metallic seals are made of perfluororubber or food-grade silicone that is resistant to high temperature and humidity and has stable chemical properties. The circuit system adopts an industrial-grade protection design with a protection level of not less than IP65, ensuring long-term stable operation in high-temperature and high-humidity fermentation environments.

[0041] During the processing of this invention, the central control system not only monitors the current real-time parameters but also possesses trend prediction capabilities based on historical data. For example, when the rate of increase in core temperature exceeds the variation range of the historical standard curve, the system predicts an impending "burnout" risk and intervenes in advance, initiating early warning-based reactor overhaul and cooling measures. This strategy, combining feedforward and feedback control, enhances the system's stability and fault tolerance.

[0042] To enable the central control system to precisely control microbial metabolism, this invention also incorporates an optical microscopy module and image recognition unit within the circulating air duct on the inner wall of the fermentation chamber. This module captures and identifies the morphological characteristics of *Aspergillus cristatus* spores in the air in real time, and counts the number of spores per unit volume; alternatively, it can be replaced with a PCR-based online microbial DNA rapid detection module. When the spore concentration reaches its peak and begins to decline, accompanied by a slowdown in the carbon dioxide release rate, the system determines that fermentation has entered the maturation stage and automatically initiates a cooling program to solidify the fermentation results, thus enhancing the system's ability to control complex biological processes.

[0043] Furthermore, the hydraulic forming machine described in this invention integrates an ultrasonic-assisted vibration module in the pressing head. Applying micro-amplitude vibrations at a specific frequency during the pressing process reduces the internal friction between tea particles, allowing the tea cake to achieve the preset compactness under relatively low static pressure. This not only reduces the damage to the internal substances of the tea leaves caused by mechanical pressure but also results in a more uniform internal structure in the formed tea cake / brick, which is beneficial for the uniform release of moisture during subsequent drying and the long-term aging of flavor compounds.

[0044] In summary, this invention, through innovations in hardware architecture, sensor detection, motion mechanisms, and control logic, constructs an automated processing system capable of deeply adapting to the complex biochemical requirements of secondary fermentation in tea. This system and method, while improving production efficiency, endow industrial tea production with the high-quality connotations of traditional artisan craftsmanship, possessing significant industry promotion value. The integrated central control system interacts with various modules in real time via an industrial bus, achieving coordinated optimization of parameters throughout the entire process—pretreatment, water adjustment, fermentation, shaping, and drying. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the overall structure of an automated secondary fermentation processing system for tea according to the present invention.

[0046] Figure 2 This is a schematic diagram of the structure of the programmable secondary fermentation module in this invention;

[0047] Figure 3 This is a schematic diagram of the adaptive flexible turning mechanism in this invention;

[0048] Figure 4 This is a schematic diagram of the automatic water metering and conveying module in this invention;

[0049] Figure 5 This is a schematic flowchart of an automated secondary fermentation processing method for tea according to the present invention.

[0050] The attached diagrams are labeled as follows: 1. Dry tea raw material pretreatment module; 2. Automatic metering and water adjustment and conveying module; 3. Programmable secondary fermentation module; 4. Automatic extrusion molding module; 5. Continuous drying and roasting module; 6. Integrated central control system; 7. Vibrating sieve; 8. Cutting and leveling machine; 9. Multi-stage vibrating sieve; 10. Magnetic separator for removing impurities; 11. Visual color sorter; 12. Real-time weighing mechanism for dry tea; 13. Non-contact moisture meter; 14. High-precision atomization... 15. Wet components; 16. Spiral mixing conveyor; 17. Ultrasonic atomizing nozzle; 18. Insulated fermentation box; 19. Multi-dimensional sensing and detection matrix; 20. Adaptive flexible turning mechanism; 21. Microenvironment adjustment unit; 22. Detector rod; 23. Three-axis gantry frame; 24. Z-axis lifting driver; 25. Rotary driver; 26. Flexible turning handle; 27. Quantitative dispensing machine; 28. Hydraulic forming machine; 29. ​​Chain dryer; 20. Drum drying machine. Detailed Implementation

[0051] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0052] This invention provides an automated secondary fermentation processing system for tea, whose overall architecture is built upon the Industrial Internet of Things and precision machining. It aims to solve the problems of quality fluctuations and reliance on manual labor in the traditional fermentation process of dark tea or Pu'er tea through closed-loop control of the entire process. (Refer to...) Figure 1-5 The automated secondary fermentation processing system for tea consists of a dry tea raw material pretreatment module 1, an automatic metering and water adjustment and conveying module 2, a programmable secondary fermentation module 3, an automatic extrusion molding module 4, a continuous drying and frying module 5, and an integrated central control system 6. These modules are organically combined through standardized industrial communication protocols and material conveying pipelines to form a highly automated operating environment from raw material input to finished product output.

[0053] In the design of the dry tea raw material pretreatment module 1, the system prioritizes the impact of raw material consistency on subsequent fermentation processes. The dry tea raw material pretreatment module 1 includes a vibrating sieve 7, a uniform cutter 8, a multi-stage shaking sieve 9, a magnetic separator 10, and a visual color sorter 11, connected in sequence. The vibrating sieve 7, as the first process, has a frame welded from high-strength carbon steel and undergoes aging treatment to eliminate internal stress. Inside the vibrating sieve 7, three layers of SUS304 stainless steel screens with different apertures are installed. The aperture of the uppermost screen is selected to be 12mm to 15mm, and its main function is to intercept large pieces of non-tea foreign matter or adhered tea lumps. The aperture of the middle layer screen is precisely set between 4mm and 6mm. This range, through extensive experimental verification, has been determined to be the most favorable dry tea sheet size for subsequent uniform water absorption and microbial penetration, used to collect raw materials that meet the process requirements. The bottom screen has a mesh size of 0.5mm, designed to remove fine dust and debris generated during the production process and prevent it from forming a viscous paste during the water conditioning stage.

[0054] The uniform cutter 8 is located adjacent to the discharge port of the vibrating screen 7. Its core component is a set of adjustable-gap rotating blades. The blades of the rotating blades are made of high-hardness alloy steel, and the blade gap can be adjusted to the micron level between 2mm and 10mm using precision adjusting bolts. The function of the uniform cutter 8 is to uniformly cut large tea leaves that exceed the preset size range. Subsequently, the material enters the multi-stage vibrating screen 9. This equipment achieves reciprocating vibration in a combined horizontal and vertical direction through an eccentric shaft drive mechanism. Its vibration frequency is locked in the low-frequency, high-amplitude range of 10Hz to 25Hz. This frequency selection can minimize physical damage to the tea cell structure while achieving efficient secondary grading.

[0055] To ensure food safety, a magnetic separator 10 is integrated into the conveying path. This device includes a set of rare-earth permanent magnet rods with a magnetic induction intensity of over 12,000 gauss. The magnetic rods are arranged in three staggered layers within a sealed conveying channel, ensuring that the material flows through a region fully covered by the strong magnetic field, thus guaranteeing the complete adsorption of minute ferromagnetic impurities in the tea leaves, such as metal fragments from mechanical wear. A visual color sorter 11, serving as the final line of defense in pre-treatment, is equipped with a full-color CCD sensor and a near-infrared sensor. The CCD sensor identifies the geometric shape and color differences of the tea leaves, while the near-infrared sensor utilizes the spectral reflectance characteristics of different substances to identify non-tea impurities such as stones, glass, and plastic. Its high-speed electromagnetic spray valve at the rear has a response delay of less than 1 ms, enabling precise airflow jetting to remove impurities during the free fall of the material, achieving a removal accuracy of over 99.9%.

[0056] The automatic metering, water adjustment, and conveying module 2 is responsible for preparing raw materials with precise moisture content for fermentation. This module includes a real-time dry tea weighing mechanism 12, a non-contact moisture detector 13, a high-precision atomizing humidification component 14, and a spiral mixing conveyor 15. The real-time dry tea weighing mechanism 12 adopts a weighing platform structure supported by four high-precision pressure sensors, achieving a static metering accuracy of 0.1%. The non-contact moisture detector 13 is installed above the feed hopper of the spiral mixing conveyor 15. Its working principle is based on the physical characteristic that moisture absorbs near-infrared spectra of specific wavelengths, enabling it to obtain the initial moisture content of the tea leaves to be fermented in real time and non-destructively while the material is flowing.

[0057] The high-precision atomizing humidification component 14 is the key actuator for achieving precise water adjustment. It includes an electromagnetic flow meter, a variable frequency water pump, and a set of ultrasonic atomizing nozzles 16 arranged on the inner wall of the spiral mixing conveyor 15. The ultrasonic atomizing nozzles 16 utilize high-frequency piezoelectric ceramic oscillation to break water molecules into extremely fine droplets with a diameter of less than 50 μm. This micron-level atomization effect ensures good penetration of water when it comes into contact with the tea surface, without forming locally overly wet droplets. The integrated central control system 6 adjusts the speed of the variable frequency water pump using closed-loop regulation logic based on the real-time difference between the initial moisture content and the preset target moisture content (usually set between 25% and 32% depending on the type of tea). The blades of the spiral mixing conveyor 15 are designed as ribbon spirals, with a 0.2 mm thick polytetrafluoroethylene anti-stick coating on the surface. This structure and material selection effectively prevents the tea leaves from clumping in a moist state, ensuring that the tea leaves remain loose after watering and enter the subsequent fermentation stage.

[0058] The programmable secondary fermentation module 3 is the core technology of this invention, consisting of several independently controlled insulated fermentation tanks 17. Each fermentation tank 17 is designed as an independent bioreactor, comprising a double-layered stainless steel insulated body, a multi-dimensional sensing matrix 18, an adaptive flexible turning mechanism 19, and a microenvironment adjustment unit 20. The inner wall of the double-layered stainless steel insulated body is made of SUS316L acid and alkali resistant stainless steel to resist corrosion from organic acids that may be generated during fermentation. The intermediate layer is filled with a 50mm thick material with a bulk density of 40kg / m³. 3 The rigid polyurethane foam material has an extremely low thermal conductivity, ensuring that heat loss during fermentation is minimized.

[0059] The multi-dimensional sensing matrix 18 achieves comprehensive sensing of the internal state of the reactor core through several sets of insertable probes 21. The probes 21 are encapsulated in food-grade 316 stainless steel sleeves, and each probe 21 has three sets of platinum resistance temperature sensors (PT100) evenly spaced vertically to monitor the temperatures at the top, middle, and bottom of the reactor core. Simultaneously, each probe 21 integrates a capacitive moisture sensor and a set of gas sampling ports. These gas sampling ports are connected to a high-precision gas analyzer outside the reactor core via PTFE tubing for real-time quantitative analysis of oxygen, carbon dioxide, and ammonia and ethanol concentrations—indicators of microbial metabolism—within the reactor core.

[0060] The adaptive flexible turning mechanism 19 adopts a biomimetic engineering design. Installed on a three-axis gantry frame 22 on the upper part of the fermentation tank 17, this mechanism possesses precise movement capabilities in three degrees of freedom: X, Y, and Z. The mechanism includes a Z-axis lifting drive 23, a rotary drive 24, and a flexible turning hand 25. The flexible turning hand 25 is made of a specially formulated food-grade silicone material with a Shore hardness precisely controlled between 55 and 65 degrees. This ensures that when inserted into the pile, it has sufficient rigidity to turn the tea leaves while also possessing sufficient toughness to avoid shearing the tea fiber. The integrated central control system 6 processes data from the multi-dimensional sensor matrix 18 in real time. When the temperature difference between the core and surface exceeds 5°C, or when the carbon dioxide concentration accumulates to above 3%, the system automatically plans the turning path. Driven by a servo motor, the flexible turning hand 25 performs a spatial spiral insertion and turning motion, spatially displacing the high-temperature, high-carbon dioxide material in the core with the low-temperature, oxygen-rich material on the surface, achieving heat dissipation, venting, and oxygenation of the pile.

[0061] Furthermore, to address the physical interference between sensor protection and the turning operation, each probe 21 in the multi-dimensional sensing matrix 18 is designed as a retractable structure. Before the adaptive flexible turning mechanism 19 enters the designated operating area, the integrated central control system 6 instructs the probes 21 within that area to retract upwards into the protective sleeve at the top of the container, driven by a pneumatic actuator, via a pneumatic distribution valve. After the turning operation is completed, the probes 21 re-insert into the pile to continue data acquisition. This precise mechanical coordination ensures continuous monitoring.

[0062] The microenvironment control unit 20 includes an ultrasonic humidifier, an electric heating array, a cooling coil, and a variable frequency circulating fan. The variable frequency circulating fan is connected to the fermentation chamber via a stainless steel air duct, which is embedded with a HEPA H13 high-efficiency air filter to ensure that every liter of air entering the chamber is rigorously purified. The integrated central control system 6 utilizes a PID control strategy to maintain a stable environment within the chamber through combined control of heating, cooling, humidification, and ventilation. Furthermore, a high-precision electronic weighing module is installed at the bottom of the chamber to monitor mass fluctuations caused by respiration and moisture evaporation in real time; this data serves as a global constraint for determining moisture content.

[0063] The automatic extrusion molding module 4 receives fermented and matured material via a sealed, automated conveyor belt. This module includes a quantitative dispensing machine 26 and a hydraulic molding machine 27. The quantitative dispensing machine 26 uses a weighing method to ensure that the weight deviation of each portion of tea to be pressed is controlled within ±0.5g. The hydraulic molding machine 27 is equipped with a pressure-displacement dual closed-loop monitoring system. During the pressing process, the output pressure of the hydraulic cylinder is slowly increased according to a preset curve between 5MPa and 20MPa, and the holding time is set between 30 seconds and 120 seconds depending on the thickness of the tea cake. The mold surface is distributed with an array of 0.2mm diameter permeable micropores to facilitate the discharge of excess air during the pressing process and moisture migration during subsequent drying. A temperature sensing element is also embedded inside the mold; if the temperature rise generated by mechanical extrusion exceeds 40℃, the system automatically activates the cooling water circulation within the mold jacket.

[0064] The continuous drying and roasting module 5 is responsible for final quality control. The chain dryer 28 employs a segmented temperature control design, with heat sourced from an air-source heat pump system. This design is more than 40% more energy-efficient than traditional coal or gas heating. The drying air velocity is controlled between 0.5 m / s and 2.0 m / s. The drum roaster 29 is located at the end of the drying process, providing precise radiant heat through infrared heating tubes. This high-temperature, instantaneous treatment stimulates the Maillard reaction of sugar-amine complexes in the tea leaves, producing the characteristic aged aroma.

[0065] The present invention also provides an automated processing method for secondary fermentation of tea based on the above system, the specific implementation steps of which are as follows:

[0066] Step S1: Pre-treatment and impurity removal of dry tea raw materials. The dry tea raw materials are first evenly fed into the vibrating sieve 7 by a feeder. Through physical sorting using three layers of 15mm, 5mm, and 0.5mm sieves, large foreign objects and powder are effectively removed. Tea leaves of intermediate size enter the cutting machine 8, where they are cut to uniform lengths under the high-speed rotation of the blade assembly. Subsequently, the material is evenly dispersed on a multi-stage vibrating sieve 9 at a frequency of 20Hz, and flows through a magnetic separator 10 to remove metallic impurities. Finally, in a visual color sorter 11, color is captured by a CCD and components are determined by near-infrared spectroscopy. A burst of high-pressure air is used to eject spoiled leaves, tea stems, and plastic fragments into the waste hopper.

[0067] Step S2: Automatic metering and water adjustment, feeding, and intelligent fermentation control. S201: Raw material metering and initial state sensing. During the conveyor belt transport of pre-treated dry tea leaves, the weighing mechanism 12 records the cumulative flow in real time, and the non-contact moisture detector 13 acquires moisture data at a sampling frequency of 50 times per second. S202: Precise closed-loop water adjustment. The integrated central control system 6 calculates the instantaneous water volume required to reach the target moisture content of 30% based on the current flow rate and initial moisture content. The variable frequency water pump responds quickly, sending the filtered water into the ultrasonic atomizing nozzle 16. Under the dual-shaft stirring of the spiral mixing conveyor 15, the atomized water is evenly attached to the surface of the tea leaves and gradually penetrates into the interior of the leaves during the transport process. S203: Automatic packing and environmental initialization. The water-adjusted tea leaves are evenly spread in the insulated fermentation box 17. The system starts the initialization program, preheating the air temperature inside the box to 40°C and increasing the relative humidity to 90%, inducing the recovery of residual enzyme activity in the tea leaves and the inoculation and growth of beneficial microorganisms (such as Aspergillus cristatus). S204: Dynamic monitoring and microbial metabolic feedback driven. During the 15-25 day fermentation cycle, the multi-dimensional sensor matrix 18 continuously collects data. When the detection rod 21 indicates that the core temperature has reached the alarm threshold of 62℃, the adaptive flexible turning mechanism 19 is activated. The flexible turning hand 25 disperses the hot spot at a speed of 15 revolutions per minute, while the variable frequency circulating fan increases the fresh air volume to remove heat from the pile. When the gas analyzer shows a carbon dioxide concentration exceeding 3.5%, the system determines that there is a risk of oxygen deficiency in the pile and automatically starts the turning and oxygenation program to guide the dominant microbial community to carry out targeted metabolic transformation.

[0068] Step S3: Fermentation Completion Determination and Automatic Extrusion Molding. The system determines whether fermentation is complete by real-time monitoring of the fingerprint spectrum of volatile metabolites and combining this with changes in the leaf color captured by an online camera (from greenish-brown to reddish-brown with an oily sheen). Once the standard is met, the fermentation chamber automatically discharges the material to the quantitative packaging machine 26. The hydraulic molding machine 27 follows a gradient pressurization program, first pre-pressing at 5MPa to expel air, and then gradually increasing the pressure to 15MPa for shaping, ensuring that the internal structure of the tea brick is compact and free of mechanical damage.

[0069] Step S4: Programmed Drying and Aroma Enhancement. The shaped tea leaves enter the chain dryer 28. Initially, low-temperature dehumidification is performed at 55℃ with the airflow set to 80% of the maximum value to remove surface free water. In the middle stage, the temperature is raised to 75℃, and the humidity of the circulating air is controlled to induce internal moisture to migrate outward. In the later stage, the temperature is maintained at 95℃ for 30 minutes to completely inactivate microorganisms and fix the color. Finally, it enters the drum dryer 29, where a thermochemical transformation is initiated by infrared radiation heat at an instantaneous high temperature of 135℃, enhancing the aged aroma and mellowness of the dry tea.

[0070] To verify the technical advantages of the system of the present invention, data demonstration is carried out through the following embodiments and comparative examples.

[0071] Example 1: An automated secondary fermentation processing system for tea provided by this invention was used to process black tea from a certain production area. Pre-treatment parameters were set as follows: sieve mesh size 5mm, cutting length 6mm, color sorting delay 0.8ms. The target moisture content was 29.5%. Fermentation control parameters: maximum core temperature 63℃, maximum carbon dioxide concentration 3.0%, and the turning interval was automatically determined by the system based on sensor feedback. The drying process employed a three-stage gradient temperature control.

[0072] Comparative Example 1: Processing was carried out using a semi-automated production line with existing technology. Watering and turning were done manually, and the moisture content was determined based on experience. Fermentation took place in a traditional open fermentation room, with environmental parameters monitored by wall-mounted thermometers and hygrometers. Manual turning was performed periodically based on experience. Drying was done using a conventional constant-temperature dryer.

[0073] Comparative Example 2: A fully automated system lacking internal pile sensing feedback and a flexible turning mechanism. Fermentation parameters were set to timed turning every 48 hours, water was applied using traditional spray nozzles, and drying was performed at a fixed temperature.

[0074] Table 1 below shows the comparative data of the above embodiments and comparative examples in terms of finished tea quality and production indicators:

[0075] Table 1: Comparison of Tea Processing Quality and Efficiency

[0076]

[0077] Analysis of the data in Table 1 shows that Example 1 has a higher water extract content than the comparative example, demonstrating that precise closed-loop temperature and humidity control and the microbial metabolic feedback mechanism can more effectively induce the transformation of internal substances. Especially in terms of quality consistency, the standard deviation of Example 1 is only 0.8, far superior to the 5.2 of Comparative Example 1, fully illustrating the excellent performance of the system of this invention in standardized production after eliminating human interference. The reduction in broken tea rate (1.2%) is attributed to the protective effect of the adaptive flexible turning mechanism 19 on the physical structure of the tea leaves.

[0078] Furthermore, the integrated central control system 6 described in this invention possesses complete data traceability capabilities. The system collects operational parameters for each batch at various nodes in real time via industrial Ethernet, including but not limited to the instantaneous flow rate curve for water adjustment, the three-dimensional temperature field evolution map during fermentation, the action log of the turning mechanism, and the humidity change trend in the drying section. This data is stored digitally in an industrial database, which can not only be used for precise traceability of product quality but also continuously optimize expert process curves for raw materials of different years and tenderness through big data analysis.

[0079] In terms of energy conservation and emission reduction, the waste heat recovery device configured in the continuous drying and roasting module 5 utilizes the heat pump cycle principle to pump the heat from the waste air discharged at the drying end back to the front-end preheating section. Actual measurements show that this configuration, under an ambient temperature of 20℃, can preheat the incoming fresh air to approximately 45℃, reducing the demand for electric heating power and keeping the overall system's unit energy consumption at a low level.

[0080] All mechanical contact components involved in this invention, such as the shaft of the spiral mixing conveyor 15, the lining of the fermentation tank 17, and the mold of the hydraulic forming machine 27, have undergone precision polishing, with their surface roughness Ra value controlled below 0.4 μm. This mirror-level surface treatment not only improves the flowability of materials, but more importantly, effectively reduces the probability of biofilm adhesion to the equipment surface. Combined with the system-integrated ozone sterilization module, the automated disinfection treatment performed after each batch ensures the long-term sterile and hygienic state of the production system.

[0081] In summary, this invention achieves transparency in the fermentation process through a multi-dimensional sensing matrix, precision in motion through a biomimetic flexible mechanism, and standardization in production through a closed-loop logic throughout the entire process. This mechatronics-biochemical integrated design effectively solves the challenge of controlling the complex biochemical process of secondary fermentation in tea production in industrial settings, providing reliable engineering and technical support for the large-scale production of high-quality dark tea and Pu'er tea.

[0082] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. An automatic processing system for secondary fermentation of tea leaves, characterized in that, include: A pre-processing module for dried tea raw materials (1) is used to perform physical grading, fixed-length cutting and impurity removal on dried tea raw materials. An automatic metering and conveying module (2) is located downstream of the dry tea raw material pretreatment module (1) and is used for closed-loop atomization water replenishment based on the initial moisture content of the tea leaves. The programmable secondary fermentation module (3) receives tea leaves after water adjustment through an automatic conveying mechanism. The programmable secondary fermentation module (3) includes several sets of independently controlled heat preservation fermentation boxes (17) for dynamically regulating the internal environment of the pile based on microbial metabolic feedback signals. Automatic extrusion molding module (4) is used to press the fermented tea leaves into tea blanks of a preset shape according to a preset pressure curve; Continuous drying and frying module (5) is used to perform gradient cooling drying and high-temperature aroma enhancement treatment on the tea blanks; as well as An integrated central control system (6) is electrically connected to each of the above modules and is used to coordinate the operation parameters of each module according to the process curve.

2. The automatic secondary fermentation processing system for tea leaves according to claim 1, characterized in that, The pre-processing module (1) for dry tea raw materials includes a vibrating sieve (7), a cutting and leveling machine (8), a multi-stage shaking sieve (9), a magnetic separator (10), and a visual color sorter (11) connected in sequence. The vibrating sieve (7) is equipped with three layers of screens with apertures of 12mm-15mm, 4mm-6mm, and 0.5mm, respectively. The magnetic separator (10) includes a rare earth permanent magnet rod assembly with a magnetic induction intensity of more than 12,000 gauss.

3. The automated secondary fermentation processing system for tea according to claim 1, characterized in that, The automatic metering and conveying module (2) includes a real-time weighing mechanism for dry tea (12), a non-contact near-infrared moisture detector (13), a high-precision atomizing humidification component (14), and a spiral mixing conveyor (15); the high-precision atomizing humidification component (14) includes an ultrasonic atomizing nozzle (16) arranged on the inner wall of the spiral mixing conveyor (15), and the droplet diameter generated by the ultrasonic atomizing nozzle (16) is less than 50μm; the blade surface of the spiral mixing conveyor (15) is coated with a polytetrafluoroethylene anti-stick coating.

4. The automated secondary fermentation processing system for tea according to claim 1, characterized in that, The programmable secondary fermentation module (3) includes a multidimensional sensing and detection matrix (18) and an adaptive flexible turning mechanism (19) set in the heat-insulating fermentation box (17); the multidimensional sensing and detection matrix (18) includes an array composed of several sets of insertable probes (21), and each probe (21) is provided with three sets of platinum resistance temperature sensors, one set of capacitive moisture sensors and one set of gas sampling holes arranged at equal intervals in the vertical direction.

5. The automated secondary fermentation processing system for tea according to claim 4, characterized in that, The adaptive flexible turning mechanism (19) is installed on the three-axis gantry frame (22) on the upper part of the heat-insulating fermentation box (17), including a Z-axis lifting driver (23), a rotary driver (24) and a flexible turning hand (25); the flexible turning hand (25) is made of food-grade silicone material; the integrated central control system (6) controls the flexible turning hand (25) to perform turning action according to the core and surface temperature difference threshold or carbon dioxide concentration threshold fed back by the multi-dimensional sensing and detection matrix (18).

6. The automated secondary fermentation processing system for tea according to claim 4, characterized in that, Each probe (21) in the multidimensional sensing and detection matrix (18) adopts a retractable structure and is connected to a pneumatic actuator; the integrated central control system (6) controls the probe (21) to retract upward to the top of the box before the adaptive flexible turning mechanism (19) performs the turning action, and to reinsert downward into the pile after the turning action is completed.

7. The automated secondary fermentation processing system for tea according to claim 1, characterized in that, The automatic extrusion molding module (4) includes a hydraulic molding machine (27), which is equipped with a pressure displacement monitoring system for adjusting the output pressure from 5MPa to 20MPa; the mold of the hydraulic molding machine (27) has a temperature sensing element embedded inside, and the mold surface is provided with an array of breathable micropores.

8. The automated secondary fermentation processing system for tea according to claim 4, characterized in that, The programmable secondary fermentation module (3) is also equipped with a nutrient solution addition unit and an ozone sterilization module; the integrated central control system (6) controls the nutrient solution addition unit to add microbial inducers to the replenishing water according to the fermentation requirements of specific tea types, and uses the ozone sterilization module to perform disinfection after the batch task is completed.

9. An automated processing method for secondary fermentation of tea based on the automated secondary fermentation processing system for tea according to any one of claims 1-8, characterized in that, Includes the following steps: Step S1: The dried tea raw materials are pre-treated by vibration sieving, fixed-length cutting, magnetic separation and visual color sorting to obtain dried tea slices with uniform specifications. Step S2: The initial moisture content of the dried tea leaves is measured in real time using a near-infrared moisture detector. The amount of water to be added is calculated and closed-loop water adjustment is performed using ultrasonic atomization. The leaves are then sent into a programmable fermentation chamber. The metabolic parameters inside the pile are monitored using a multi-dimensional sensor matrix. The flexible turning mechanism is controlled to perform adaptive turning based on temperature difference or gas concentration feedback. Step S3: After determining that the fermentation is mature, discharge the material, and then perform hydraulic flexible extrusion molding according to a preset pressure curve through quantitative packaging; Step S4: The shaped tea leaves are sent into a dryer for gradient temperature-controlled drying and then subjected to high-temperature aroma enhancement treatment in a drum.

10. The automated processing method for secondary fermentation of tea according to claim 9, characterized in that: In step S2, the target moisture content for closed-loop water conditioning is 25% to 32%; when the temperature difference between the core and surface exceeds 5°C or the carbon dioxide concentration exceeds 3%, automatic reactor turning is triggered; in step S4, gradient temperature-controlled drying sequentially includes a low-temperature dehumidification section of 50°C-60°C, a medium-temperature migration section of 70°C-80°C, and a quality fixation section above 90°C.

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