Double-layer stainless steel probiotic fermentation device and method capable of accurately controlling temperature and humidity

Abstract

The invention relates to the technical field of microbial fermentation, and discloses a double-layer stainless steel probiotic fermentation device with precise temperature and humidity control and a fermentation method. The device comprises a double-layer stainless steel tank body (an inner-layer fermentation cavity and an outer-layer temperature control interlayer), a temperature control system (comprising a spiral heating pipe, a cooling coil and a PID temperature controller), a humidity adjusting module (comprising an ultrasonic nebulizer, a condensation dehumidification plate and a humidity controller), a self-adaptive stirring system (comprising a variable frequency motor, a liftable stirring shaft and a detachable paddle) and a central control system. According to the method, accurate synergy of parameters is achieved through device pretreatment and staged regulation and control (a proliferation period, a stable period and a metabolic period). The device and the method solve the problems of insufficient temperature and humidity control precision, poor stirring adaptability, weak parameter synergy and insufficient material safety of the existing equipment, remarkably improve the viable count of probiotics and the yield of metabolites, and are suitable for the field of biological fermentation.

Description

Technical Field

[0001] This invention relates to the field of bio-fermentation technology, and specifically discloses a double-layer stainless steel probiotic fermentation device and method with precise temperature and humidity control. Background Technology

[0002] Probiotics have broad application prospects in food, medicine, agriculture, and other fields. The cultivation and fermentation process of probiotics has strict requirements for environmental parameters such as temperature, humidity, and agitation. Traditional probiotic fermentation equipment often lacks precision in temperature and humidity control, making it difficult to meet the optimal conditions for probiotic growth and reproduction, resulting in low cell activity and product yield. For example, some fermenters use simple water baths or electric heating for temperature control, which has poor precision and is prone to localized overheating or undercooling; humidity control is even more rudimentary, relying heavily on ambient humidity or simple humidification methods, making precise adjustment difficult. Furthermore, the agitation systems of existing fermentation equipment are usually fixed or have limited adjustment ranges, unable to be flexibly adjusted according to the needs of each fermentation stage, affecting the uniform growth of cells and the accumulation of metabolites. These problems severely restrict the efficiency and product quality of probiotic fermentation. Therefore, developing a probiotic fermentation device and corresponding fermentation method that can achieve precise temperature and humidity control and flexible agitation is of great significance for improving the success rate and economic benefits of probiotic fermentation. Summary of the Invention

[0003] The purpose of this invention is to solve the technical problems of insufficient temperature and humidity control accuracy, poor adaptability of stirring system, weak parameter coordination and insufficient material safety in existing probiotic fermentation devices, and to provide a double-layer stainless steel probiotic fermentation device with precise temperature and humidity control, staged stirring adaptation, coordinated parameter linkage and stable material.

[0004] In a first aspect, the present invention provides a double-layer stainless steel probiotic fermentation device with precise temperature and humidity control, comprising: The system comprises a double-layered stainless steel tank, with the inner layer serving as a fermentation chamber and the outer layer forming a sealed temperature-controlled interlayer filled with a heat-conducting medium. Temperature and humidity sensors are embedded in the tank walls of the fermentation chamber. A sterile inoculation port and an exhaust valve are located at the top of the inner tank wall. The temperature control system includes a spiral heating element, a cooling coil, and a circulating pump located within the interlayer, as well as a PID temperature controller electrically connected to the temperature sensors. The PID temperature controller adjusts the power of the heating element and the flow rate of the cooling coil. The inlet of the circulating pump is connected to the bottom of the interlayer, and the outlet is connected to the top of the interlayer. The humidity control module includes an ultrasonic atomizer located at the top of the fermentation chamber, a condenser dehumidifier located at the bottom of the fermentation chamber, and a humidity controller electrically connected to the humidity sensors. The humidity controller can activate the ultrasonic atomizer and the condenser dehumidifier. An adaptive stirring system includes a variable frequency motor, a height-adjustable stirring shaft, and detachable turbine blades and anchor blades. The height-adjustable stirring shaft is located inside the fermentation chamber. The output end of the variable frequency motor is connected to the height-adjustable stirring shaft, and the height-adjustable stirring shaft can adjust the height of the turbine blades and the anchor blades. A central control system is electrically connected to the PID temperature controller, the humidity controller, the variable frequency motor, and the height-adjustable stirring shaft.

[0005] The double-walled stainless steel tank features an independent fermentation space and temperature control system through a separate inner and outer layer design. The inner layer ensures the purity of the fermentation system, while the outer layer achieves uniform temperature control throughout the entire area through the circulation of a heat-conducting medium. The temperature control system integrates bidirectional heating and cooling regulation, combined with a PID algorithm to achieve sub-Celsius precision control. The humidity control module innovatively adopts a "humidification-dehumidification" linkage mechanism to dynamically balance the humidity in the fermentation chamber. The adaptive stirring system precisely matches the fluid dynamics requirements of different growth stages of probiotics through optimized combinations of blade type, height, and speed. The central control system serves as the core hub, enabling real-time linkage and staged switching of various parameters, constructing a collaborative control system for "environment-growth-metabolism".

[0006] In some embodiments of the present invention, the inner layer of the double-layer stainless steel tank is made of 316L stainless steel, and the outer layer is made of 304 stainless steel. The heat-conducting medium in the temperature-controlled interlayer is food-grade silicone oil, and a vacuum valve is provided at the top of the interlayer. 316L stainless steel contains molybdenum and has excellent pitting corrosion resistance, which can resist long-term corrosion from organic acids in the fermentation system. 304 stainless steel has high mechanical strength, ensuring the structural stability of the tank as the outer layer. Food-grade silicone oil has a stable thermal conductivity (approximately 0.15 W / (m・K) at 25℃) and its viscosity is minimally affected by temperature, ensuring uniform heat transfer. The vacuum valve can evacuate the interlayer to a negative pressure state, reducing air thermal resistance and improving the temperature control response speed by more than 30%.

[0007] In some embodiments of the present invention, the temperature sensor is a platinum resistance thermometer, and the humidity sensor is a capacitive sensor. Both are embedded in the inner tank wall through a sterile seal, with the probe end in direct contact with the fermentation chamber. The platinum resistance thermometer has a measurement accuracy of ±0.1℃ and a long-term stability error of less than 0.2℃ / year, capable of capturing minute temperature fluctuations. The capacitive humidity sensor has a response time of less than 2s, a measurement range of 10%~90% RH, an accuracy of ±2% RH, and can provide real-time feedback on humidity dynamics. The sterile seal is made of polytetrafluoroethylene and is laser-welded to the tank wall to ensure no risk of leakage or contamination.

[0008] In some embodiments of the present invention, the lifting mechanism on the liftable stirring shaft is an electric push rod, which allows the turbine blades and the anchor blades to be adjusted within the height range of 1 / 3 to 2 / 3 of the fermentation chamber; the turbine blades are inclined at 30 to 45°, and the edges of the anchor blades are bonded with wear-resistant rubber strips. The positioning accuracy of the electric push rod reaches ±1mm, which can precisely control the blade height to match different liquid levels; the tilt angle design of the turbine blades can generate axial thrust, promote the circulation of fluids between the upper and lower layers, improve the mixing uniformity by 40%, and is suitable for substrate dispersion during the proliferation period; the rubber strips of the anchor blades can adhere to the tank wall and scrape, reducing culture medium adhesion, avoiding local metabolite accumulation, and adapting to high viscosity systems during the metabolic period.

[0009] In some embodiments of the present invention, the spiral heating tube is a seamless stainless steel tube, spirally wound along the outer wall of the inner layer of the double-layer stainless steel tank; the cooling coil is a copper corrugated tube, fitted to the outer side of the spiral heating tube and fixed with cable ties. The spiral winding increases the contact area between the heating tube and the inner tank wall by 60%, significantly improving the uniformity of heat distribution; the thermal conductivity of the copper corrugated tube (approximately 401 W / (m·K)) is more than 10 times that of stainless steel, and its fit against the heating tube enables rapid cooling, reducing the heating-cooling switching time to within 5 minutes, far superior to the 15 minutes of traditional devices.

[0010] Secondly, this invention provides a method for precise temperature and humidity control of probiotic fermentation based on the above-mentioned device, comprising the following steps: S1. Device pretreatment: The double-layer stainless steel tank is cleaned by CIP with the following parameters: pressure 0.8~1.2MPa, temperature 60~80℃, time 15~20 min. A heat-conducting medium is introduced, and a vacuum is drawn to -0.06~-0.04MPa. The parameters are preset by the central control system; S2. Culture medium inoculation: The sterilized culture medium is injected into the fermentation chamber, the volume of which is 60%~70% of the volume of the fermentation chamber. Activated probiotic solution is inoculated at an inoculation rate of 5%~8%; S3. Staged control: The central control system is activated to monitor and adjust the temperature, humidity, and stirring parameters in real time; S4. Fermentation completion: The fermentation broth is collected, centrifuged, and freeze-dried to complete the fermentation.

[0011] The pretreatment process employs CIP cleaning (pressure 0.8~1.2 MPa, temperature 60~80℃, time 15~20 min) to efficiently remove residual impurities and microorganisms from the tank, ensuring a sterile fermentation environment and preventing contamination. Vacuuming and preset parameters in the central control system lay the foundation for subsequent temperature and humidity control, reducing human error and achieving automated initial control. The culture medium is filled to 60%~70%, providing ample fermentation space (avoiding liquid overflow or restricted agitation) while ensuring effective contact between nutrients and bacteria. An inoculum volume of 5%~8% allows for rapid probiotic proliferation, shortening the fermentation cycle. Phased control, through real-time monitoring and parameter adjustment, ensures optimal environment throughout the fermentation process. Final centrifugation and freeze-drying maximize probiotic activity, facilitating product storage and application.

[0012] In some embodiments of the present invention, the parameters preset by the central control system in step S1 are as follows: Proliferation period: temperature 37±0.5℃, humidity 60%±2%, stirring speed of the turbine blade 150~200 rpm, height of the turbine blade at 2 / 3 of the fermentation chamber, the proliferation period is 0~12 h; Stabilization period: temperature 35±0.5℃, humidity 70%±2%, stirring speed of both the turbine blade and the anchor blade 100~150 rpm, height of both the turbine blade and the anchor blade at 1 / 2 of the fermentation chamber, the stabilization period is 12~24 h; Metabolism period: temperature 36±0.5℃, humidity 50%±2%, stirring speed of the anchor blade 50~100 rpm, height of the anchor blade at 1 / 3 of the fermentation chamber, the metabolism period is 24~36 h. Proliferation phase (0~12h): 37±0.5℃ is the suitable temperature for rapid probiotic proliferation, and 60%±2% humidity provides a balanced moisture environment; the turbine blades stir at 150~200rpm at 2 / 3 height to enhance liquid convection, promote the uniform distribution of oxygen and nutrients, and accelerate bacterial proliferation. Stabilization phase (12~24h): The temperature is slightly lowered to 35±0.5℃ to reduce excessive energy consumption by the bacteria; 70%±2% humidity meets the water requirements of the metabolically active phase; the turbine blades and anchor blades stir synergistically at 1 / 2 height (100~150rpm) to ensure mixing of materials in the upper and lower layers and the bottom, avoid uneven local concentration, and maintain stable bacterial growth. Metabolic phase (24~36h): 36±0.5℃ is suitable for metabolite synthesis; 50%±2% humidity reduces the dilution of products by moisture; anchor-type paddles at 1 / 3 height with low-speed stirring at 50~100rpm avoid high-speed damage to metabolites while promoting metabolic reactions of materials at the bottom, increasing product accumulation. Overall, the parameters at each stage are precisely matched with the growth characteristics of probiotics, significantly increasing the number of viable bacteria and the yield of target metabolites.

[0013] In some embodiments of the present invention, in step S3, the vacuum degree of the interlayer is -0.06 MPa during the proliferation phase and -0.08 MPa during the stationary and metabolic phases; the medium circulation flow rate of the circulating pump is 5~8 L / min.

[0014] Differentiated settings for the jacket vacuum level and circulating pump flow rate further enhance temperature control precision: During the proliferation phase, the vacuum level is -0.06 MPa (a smaller absolute value), reducing the thermal resistance between the heat transfer medium and the tank, enhancing heat transfer efficiency, and quickly reaching and maintaining the temperature required for proliferation; during the stationary and metabolic phases, the vacuum level is -0.08 MPa (a larger absolute value), reducing interference from the external environment on the tank temperature, improving insulation stability, and adapting to the temperature requirements for stable bacterial growth and metabolism. The circulating pump flow rate is 5~8 L / min, ensuring sufficient circulation of the heat transfer medium within the jacket, avoiding localized temperature deviations, improving the temperature uniformity of the fermentation chamber, providing a stable temperature environment for probiotics, and reducing growth inhibition caused by temperature fluctuations.

[0015] In some embodiments of the present invention, during S3, fermentation gas is released through the exhaust valve every 1.8 to 2.2 hours during the proliferation period, for 28 to 32 seconds each time, and during the stationary and metabolic periods, it is released once every 3.8 to 4.2 hours, for 28 to 32 seconds each time.

[0016] Targeted venting frequency and duration settings optimize the fermentation gas environment: During the growth phase, probiotics metabolize vigorously, producing more gas (such as carbon dioxide), so venting is performed every 1.8~2.2 hours to promptly remove excess gas and prevent excessive pressure inside the tank from inhibiting bacterial growth. During the stationary and metabolic phases, gas production decreases, so venting is performed every 3.8~4.2 hours to reduce the risk of contamination from frequent venting. Each venting session lasts 28~32 seconds (approximately 30 seconds), effectively releasing harmful gases while avoiding sudden pressure drops that could affect environmental stability. This balance between venting efficiency and maintaining a sterile environment ensures the normal growth and metabolism of probiotics.

[0017] In some embodiments of the present invention, in step S4, the centrifugation parameters of the fermentation broth are 4000~6000 rpm, 4~8℃, 15~20 min, and the freeze-drying parameters are pre-freezing at -40~-50℃, sublimation at 20~30℃, desorption at 30~40℃, and vacuum at 10~30 Pa.

[0018] Optimization of centrifugation and freeze-drying parameters maximizes the retention of probiotic activity and improves product stability: Centrifugation parameters (4000~6000 rpm, 4~8℃, 15~20 min): Moderate speed and time allow for efficient separation of bacterial cells and fermentation broth; the low temperature of 4~8℃ avoids heat damage to probiotics from high temperatures, ensuring that the bacterial activity is not destroyed after centrifugation. Freeze-drying parameters (pre-freezing -40~-50℃, sublimation 20~30℃, desorption 30~40℃, vacuum 10~30 Pa): Ultra-low temperature pre-freezing avoids excessively large ice crystals that damage cell structure; the gradient temperature sublimation and desorption process efficiently removes moisture in a vacuum environment while preventing bacterial cell inactivation due to high temperatures; low vacuum (10~30 Pa) accelerates water sublimation, ultimately yielding a product with high activity and low water content, significantly extending shelf life and facilitating subsequent processing and application.

[0019] The beneficial effects of this invention are as follows: 1. The temperature control system, consisting of a double-layer stainless steel tank, a sealed temperature-controlled jacket filled with a heat-conducting medium, a spiral heating tube, a cooling coil, and a circulating pump, combined with a PID temperature controller, achieves precise, rapid, and stable adjustment and control of the temperature inside the fermentation chamber, avoiding local overheating or overcooling and providing the optimal temperature environment for the growth of probiotics.

[0020] 2. The humidity control module adopts a combination of ultrasonic atomizer and condenser dehumidification plate, and is linked by humidity controller. It can realize bidirectional and precise adjustment of humidity in fermentation chamber, meet the specific humidity requirements of probiotics at different growth stages, and effectively avoid the impact of excessively high or low humidity on bacterial activity.

[0021] 3. The adaptive stirring system adopts a variable frequency motor, a height-adjustable stirring shaft, and detachable turbine blades and anchor blades, which allows the stirring speed and blade height to be flexibly adjusted according to the fermentation stage. This achieves uniform mixing of the fermentation broth and oxygen transfer, while avoiding shear damage to the cells, thus improving fermentation efficiency and cell activity.

[0022] 4. The central control system integrates the control of temperature, humidity and stirring parameters, realizing the automation and intelligent management of the fermentation process, improving the convenience of operation and the stability of fermentation.

[0023] 5. A staged fermentation method is adopted. Based on the physiological characteristics of different growth stages of probiotics (proliferation period, stationary period, and metabolic period), parameters such as temperature, humidity, stirring speed and impeller height are precisely set and adjusted to maximize the optimization of fermentation conditions and significantly improve the yield and activity of probiotics.

[0024] 6. The CIP cleaning, heat transfer medium filling, and vacuuming operations in the pretreatment process, as well as the regular exhaust gas discharge during fermentation, ensure the sterility and stability of the fermentation environment, further guaranteeing the fermentation success rate and product quality. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the fermentation chamber and central control system in an embodiment of the present invention; Figure 2 This is a front view of the structure of an embodiment of the present invention.

[0026] Attached reference numerals: 1-Double-layer stainless steel tank, 2-Outer layer, 3-Inner layer, 4-Fermentation chamber, 5-Jack, 6-Cooling coil, 7-Spiral heating tube, 8-Circulating pump, 9-PID temperature controller, 10-Aseptic inoculation port, 11-Vacuum valve, 12-Exhaust gas discharge valve, 13-Heat transfer medium, 14-Ultrasonic atomizer, 15-Temperature sensor, 16-Humidity sensor, 17-Turbine blade, 18-Anchor blade, 19-Variable frequency motor, 20-Liftable rotating shaft, 21-Condensation dehumidification plate, 22-Humidity controller, 23-Central control system. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0028] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0029] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0030] In the description of the embodiments of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "horizontal," "inner," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationships commonly used when the product of the invention is in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first," "second," "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0031] Furthermore, the use of terms such as "horizontal" does not imply that the component must be absolutely horizontal or suspended, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to vertical, and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0032] In the description of the embodiments of the present invention, "multiple" means at least two.

[0033] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0034] Example 1 Please see Figures 1-2 As shown, the present invention provides a double-layer stainless steel probiotic fermentation device with precise temperature and humidity control, which mainly includes a double-layer stainless steel tank 1, a temperature control system, a humidity adjustment module, an adaptive stirring system, and a central control system 23.

[0035] The double-layered stainless steel tank 1 is the main body of the fermentation device. Its inner layer 3 is the fermentation chamber 4, used to contain the probiotic culture medium. A sealed temperature-controlled interlayer 5 is formed between the outer layer 2 and the inner layer 3. This interlayer 5 is filled with a heat-conducting medium 13 for heat transfer. In a preferred embodiment, the inner layer 3 of the double-layered stainless steel tank 1 is made of 316L stainless steel, and the outer layer 2 is made of 304 stainless steel. 316L stainless steel has excellent corrosion resistance and biocompatibility, making it suitable for direct contact with the culture medium; 304 stainless steel has good mechanical strength and cost-effectiveness. The heat-conducting medium 13 in the temperature-controlled interlayer 5 is preferably food-grade silicone oil, which has good thermal stability, thermal conductivity, and is non-toxic, ensuring the safety of the fermentation process. A vacuum valve 11 is provided at the top of the interlayer 5 for evacuating the interlayer 5 during device pretreatment to improve heat conduction efficiency and temperature control accuracy. Temperature sensors 15 and humidity sensors 16 are embedded in the tank wall of the fermentation chamber 4 for real-time monitoring of the temperature and humidity inside the fermentation chamber 4. In a preferred embodiment, the temperature sensor 15 is a platinum resistance sensor, and the humidity sensor 16 is a capacitive sensor. Both are embedded in the inner layer 3 tank wall through a sterile seal, with the probe end in direct contact with the fermentation chamber 4 to ensure measurement accuracy and a sterile environment. The top of the inner layer 3 tank wall is provided with a sterile inoculation port 10 and a waste gas exhaust valve 12. The sterile inoculation port 10 is used to inoculate bacterial solution and culture medium under sterile conditions, while the waste gas exhaust valve 12 is used to discharge metabolic waste gas while maintaining pressure balance within the fermentation chamber 4.

[0036] Temperature control system: Used for precise control of the temperature within the fermentation chamber 4. It includes a spiral heating tube 7, a cooling coil 6, and a circulating pump 8 located within the jacket 5, as well as a PID temperature controller 9 electrically connected to the temperature sensor 15. The spiral heating tube 7 is a seamless stainless steel tube, spirally wound along the outer wall of the inner layer 3 of the double-layer stainless steel tank 1 to ensure uniform heating. The cooling coil 6 is a copper corrugated pipe, fitted to the outer side of the spiral heating tube 7 and secured with cable ties for efficient cooling. The inlet of the circulating pump 8 is connected to the bottom of the jacket 5, and the outlet is connected to the top of the jacket 5, forming a circulation loop for the heat transfer medium 13, ensuring uniform temperature of the heat transfer medium 13 within the jacket 5. The PID temperature controller 9 receives the signal from the temperature sensor 15 and, based on a preset temperature value, adjusts the power of the heating tube and the flow rate of the cooling coil 6 to achieve precise PID (proportional-integral-derivative) control of the temperature of the fermentation chamber 4, keeping temperature fluctuations within a minimal range.

[0037] Humidity control module: Used for precise control of humidity within fermentation chamber 4. It includes an ultrasonic atomizer 14 located at the top of fermentation chamber 4, a condenser / dehumidifier plate 21 located at the bottom of fermentation chamber 4, and a humidity controller 22 electrically connected to a humidity sensor 16. The ultrasonic atomizer 14 atomizes water into tiny particles through high-frequency vibration, increasing the humidity within fermentation chamber 4. The condenser / dehumidifier plate 21 condenses water vapor in the air through cooling, thereby reducing humidity. The humidity controller 22 receives signals from the humidity sensor 16 and, based on a preset humidity value, activates the ultrasonic atomizer 14 and the condenser / dehumidifier plate 21 to achieve bidirectional, precise humidity control within fermentation chamber 4.

[0038] An adaptive stirring system is used for uniform mixing and gas transfer of the fermentation broth. It includes a variable frequency motor 19, a height-adjustable stirring shaft, and detachable turbine blades 17 and anchor blades 18. The height-adjustable stirring shaft is located within the fermentation chamber 4. The output end of the variable frequency motor 19 is connected to the height-adjustable stirring shaft, with each end connected to a different side of the shaft. This allows for different rotational speeds on both sides, facilitating control of the turbine blades 17 and anchor blades 18, and enabling stepless adjustment of the stirring speed through frequency conversion control. The height of the turbine blades 17 and anchor blades 18 can be adjusted to meet the stirring intensity requirements of different fermentation stages. In a preferred embodiment, the lifting mechanism on the height-adjustable stirring shaft is an electric push rod, allowing the turbine blades 17 and anchor blades 18 to be adjusted within the 1 / 3 to 2 / 3 height range of the fermentation chamber 4. This allows the stirring blades to cover different depths of the fermentation broth, achieving more uniform mixing. The turbine blades 17 are inclined at 30-45°, a design that helps generate axial and radial flow, improving mixing efficiency and oxygen transfer. The edges of the anchor blades 18 are bonded with wear-resistant rubber strips, which effectively scrape away biofilm from the tank walls, preventing bacterial adhesion and reducing wear on the tank walls. The turbine blades 17 and anchor blades 18 are detachable for easy cleaning and replacement to accommodate the fermentation needs of different microbial strains.

[0039] The central control system 23 is the "brain" of the entire device, connected to the PID temperature controller 9, humidity controller 22, variable frequency motor 19, and liftable stirring shaft. It integrates monitoring, control, and data recording functions for temperature, humidity, and stirring parameters. Based on a preset fermentation program, it automatically adjusts the operating status of each module, achieving automated and intelligent management of the fermentation process. Users can set and modify fermentation parameters, view the fermentation status in real time, and perform fault diagnosis through the central control system 23.

[0040] Example 2 This embodiment provides a fermentation method based on a double-layer stainless steel probiotic fermentation device with precise temperature and humidity control. The probiotic used is Lactobacillus plantarum. The specific steps are as follows: Pre-treatment: The double-walled stainless steel tank 1 is cleaned using CIP (Clean-In-Place) with the following parameters: pressure 1.0 MPa, temperature 70℃, and time 18 min. After cleaning, food-grade silicone oil (filling volume 85% of the jacket 5 volume) is injected into the temperature-controlled jacket 5, and a vacuum is applied to -0.05 MPa. Three-stage parameters are preset via the central control system 23. Proliferation period (0~12 h): temperature 37℃, humidity 60%, turbine speed 180 rpm, blade height at 4 2 / 3 of the fermentation chamber; Stabilization period (12~24 h): temperature 35℃, humidity 70%, turbine propeller + anchor propeller linkage speed 120rpm, propeller height located at 4 1 / 2 of the fermentation chamber; Metabolic period (24~36 h): temperature 36℃, humidity 50%, anchor paddle speed 80 rpm, paddle height located at 4 1 / 3 of the fermentation chamber.

[0041] Culture medium inoculation: The culture medium formula is as follows: 10 wt% glucose, 5 wt% yeast extract, 3 wt% fructooligosaccharides, 0.3 wt% potassium dihydrogen phosphate, 0.2 wt% magnesium sulfate, with the remainder being deionized water. The sterilized culture medium is injected into fermentation chamber 4 (filling to 65% of its volume), and activated *Lactobacillus plantarum* culture (viable count 10⁻⁶) is inoculated at a 6% inoculum rate. 9 (CFU / mL).

[0042] Phased regulation: During the proliferation period: the vacuum level of the temperature-controlled jacket 5 is maintained at -0.06 MPa, and the flow rate of the circulation pump 8 is 6 L / min; gas is released for 30 seconds every 2 hours through the exhaust valve 12. Stabilization period: Vacuum level of temperature control jacket 5 is adjusted to -0.08 MPa, circulation pump 8 flow rate is 7 L / min; gas is released for 30 s every 4 h; Metabolic phase: Maintain vacuum level -0.08 MPa, circulation pump 8 with a flow rate of 6 L / min; release gas for 30 seconds every 4 hours; The entire process is regulated in real time by a central control system 23, with temperature fluctuations ≤ ±0.3℃ and humidity fluctuations ≤ ±1.5%.

[0043] Post-fermentation treatment: After fermentation for 36 h, the fermentation broth was collected and filtered through a 100-mesh filter. The centrifugation parameters were 5000 rpm, 6℃, and 18 min. The freeze-drying parameters were pre-freezing at -45℃, sublimation at 25℃, desorption at 35℃, and vacuum at 20 Pa.

[0044] Results: The viable count of Lactobacillus plantarum after freeze-drying was 1.3 × 10¹¹ CFU / g, and the total short-chain fatty acid content was 88 mmol / L.

[0045] Example 3 This embodiment provides a method for Bifidobacterium fermentation based on the above-described device, the steps of which are as follows: Pretreatment of the device: CIP cleaning parameters: pressure 0.8 MPa, temperature 60℃, time 20 min; silicone oil injected into temperature control jacket 5 (80% filling), vacuumed to -0.04 MPa; preset parameters: Proliferation period (0~12 h): temperature 37.5℃, humidity 62%, turbine propeller speed 150 rpm, height 2 / 3; Stabilization period (12~24 h): temperature 34.5℃, humidity 68%, dual propeller linkage speed 100 rpm, height 1 / 2; Metabolic period (24~36 h): temperature 36.5℃, humidity 48%, anchor propeller speed 50 rpm, height 1 / 3.

[0046] Culture medium inoculation: Culture medium formula: lactose 8 wt%, peptone 6 wt%, inulin 2 wt%, dipotassium hydrogen phosphate 0.4 wt%, calcium chloride 0.1 wt%, balance water; the liquid volume is 60% of the fermentation chamber volume, and Bifidobacterium activated bacterial solution (viable count 10⁻⁶) is inoculated at a 5% inoculum rate. 9 (CFU / mL).

[0047] Phased regulation: Propagation period: vacuum degree -0.06 MPa, circulation pump 8 with a flow rate of 5 L / min, exhausting every 2.2 h for 32 s; Stabilization period: vacuum degree -0.08 MPa, circulation pump 8 flow rate 8 L / min, exhaust every 4.2 h for 32 s; Metabolic period: vacuum degree -0.08 MPa, circulation pump 8 flow rate 5 L / min, exhaust every 4.2 h for 32 s.

[0048] Post-fermentation treatment: After fermentation for 36 hours, the fermentation broth was centrifuged (4000 rpm, 4℃, 20 min) and freeze-dried (pre-freezing at -40℃, sublimation at 20℃, desorption at 30℃, vacuum degree 10 Pa).

[0049] Results: The viable count of Bifidobacterium after freeze-drying was 9.2 × 10¹ 0 CFU / g, total short-chain fatty acids 75 mmol / L.

[0050] Comparative Example 1 After cleaning the tank, inject the same culture medium as in Example 1 (70% full), and inoculate with Lactobacillus plantarum at a 6% inoculum rate; The entire process is kept at a constant temperature of 37℃ (water bath heating, temperature fluctuation ±2℃), with no humidity control, a fixed turbine propeller speed of 150rpm, and manual exhaust once every 8 hours. After fermentation for 48 h, the mixture was centrifuged (5000 rpm, 25℃, 15 min) and freeze-dried (parameters same as in Example 1).

[0051] Comparative Example 2 The device of this invention is used, but the parameters are fixed throughout: temperature 36℃, humidity 60%, turbine propeller speed 120 rpm, and no vacuum adjustment. The steps are as follows: The device preprocessing is the same as in Example 1, except that a single parameter is preset; Inoculation and culture medium are the same as in Example 1; After fermentation for 36 hours, the post-fermentation treatment was the same as in Example 1.

[0052] Experimental Example 1 Test objective: To verify the accuracy of temperature and humidity control during the fermentation process in Examples 2 and 3 and Comparative Examples 1 and 2.

[0053] Test method: A high-precision temperature and humidity recorder (accuracy ±0.1℃, ±1%) was used to set up monitoring points at the upper, middle and lower parts of the fermentation chamber to continuously record the temperature and humidity data during the proliferation period (0~12h), the stationary period (12~24h) and the metabolic period (24~36h). The fluctuation range of each stage was calculated and the results are shown in Table 1.

[0054] Table 1 - Temperature and Humidity Control Accuracy Structure

[0055] Results analysis: The temperature fluctuation of Examples 2 and 3 was ≤ ±0.4℃ and the humidity fluctuation was ≤ ±1.8%, which was significantly lower than that of Comparative Example 1 (traditional device without precise control) and Comparative Example 2 (no staged parameter coordination). This proves that the present invention solves the problem of insufficient temperature and humidity control accuracy of existing devices through a double-layer tank temperature control system and staged humidity adjustment.

[0056] Experimental Example 2 Test Objective: To evaluate the impact of different stirring systems on the mixing uniformity and dissolved oxygen efficiency of the fermentation broth. Test Method: Mixing uniformity: Fluorescent tracers were added to the fermentation broth, and samples were taken during the proliferation period (10 h), stationary period (20 h), and metabolic period (30 h) to determine the concentration deviation rate of tracers in the upper, middle, and lower layers. Dissolved oxygen efficiency: The dissolved oxygen value (DO) of the fermentation broth was monitored in real time using a dissolved oxygen electrode, and the average DO value at each stage was calculated. The results are shown in Table 2.

[0057] Table 2 Average DO values ​​for each stage

[0058] Results Analysis: Examples 2 and 3, by switching the blade type (turbine blade / anchor blade) and height in stages, achieved a concentration deviation rate of ≤3.8% and a dissolved oxygen efficiency of ≥6.5 mg / L, which were significantly better than Comparative Example 1 (fixed blade, uneven mixing) and Comparative Example 2 (single rotation speed, insufficient dissolved oxygen). This demonstrates that the stirring system of the present invention has stronger adaptability and solves the problem of poor adaptability of the stirring system of the existing device.

[0059] Experimental Example 3 Test objective: To verify the effect of synergistic regulation of parameters such as temperature, humidity, and agitation on viable bacterial count and metabolites.

[0060] Test methods: After fermentation, the viable cell count was determined by plate counting and the total amount of short-chain fatty acids (SCFA) was determined by gas chromatography.

[0061] Table 3 - Total Short-Chain Fatty Acids (SCFAs)

[0062] Results analysis: The viable bacteria count in Examples 2 and 3 was 200-300 times higher than that in Comparative Example 1, and the total SCFA was increased by 50%-110%, which was better than that in Comparative Example 2 where the parameters were not coordinated. This proves that the present invention solves the problem of weak parameter coordination in the prior art by controlling parameters in stages (such as high temperature and high speed during the proliferation period and low temperature and low speed during the metabolic period).

[0063] Experiment Example 4 Test objective: To evaluate the impact of the double-walled stainless steel tank material on the safety of the fermentation broth.

[0064] Test methods: After fermentation, the leaching of heavy metals (Cr, Ni, Mn) in the fermentation broth was detected by inductively coupled plasma mass spectrometry (ICP-MS); the residual bacterial count in the tank was determined by colony counting (to assess the impact of the smoothness of the inner wall on contamination). The results are shown in Table 4.

[0065] Table 4 - Heavy metal leaching and residual bacteria in the tank

[0066] Results Analysis: Examples 2 and 3 used 316L stainless steel inner layers (polishing precision Ra≤0.8μm), and no heavy metal leaching was detected. The residual bacterial count was <10 CFU / cm², which was significantly better than Comparative Example 1 (single layer ordinary stainless steel) and Comparative Example 2 (low precision polishing). This proves that the material safety of the present invention is higher and solves the problem of insufficient material safety in existing devices.

[0067] Conclusion: Experiments 1-4 show that Embodiments 1 and 2 of the present invention effectively solve the four major technical problems of existing probiotic fermentation devices by using precise temperature and humidity control, an adaptive stirring system, staged parameter coordination, and high-safety materials, and significantly improve fermentation efficiency and product quality.

[0068] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A double-layer stainless steel probiotic fermentation device with precise temperature and humidity control, characterized in that, include: The double-layer stainless steel tank has an inner layer that serves as a fermentation chamber, and a sealed temperature-controlled interlayer formed between the outer layer and the inner layer. The interlayer is filled with a heat-conducting medium. Temperature and humidity sensors are embedded in the tank wall of the fermentation chamber, and a sterile inoculation port and an exhaust valve are provided at the top of the inner tank wall. The temperature control system includes a spiral heating tube, a cooling coil, and a circulating pump disposed in the interlayer, as well as a PID temperature controller electrically connected to the temperature sensor. The PID temperature controller can adjust the power of the heating tube and the flow rate of the cooling coil. The inlet of the circulating pump is connected to the bottom of the interlayer, and the outlet of the circulating pump is connected to the top of the interlayer. The humidity control module includes an ultrasonic atomizer located at the top of the fermentation chamber, a condensation dehumidification plate located at the bottom of the fermentation chamber, and a humidity controller electrically connected to the humidity sensor. The humidity controller can link the ultrasonic atomizer and the condensation dehumidification plate. An adaptive stirring system includes a variable frequency motor, a liftable stirring shaft, and detachable turbine blades and anchor blades. The liftable stirring shaft is located inside the fermentation chamber. The output end of the variable frequency motor is connected to the liftable stirring shaft. The liftable stirring shaft can adjust the height of the turbine blades and the anchor blades. The central control system is electrically connected to the PID temperature controller, the humidity controller, the variable frequency motor, and the liftable stirring shaft, respectively.

2. The apparatus according to claim 1, characterized in that, The inner layer of the double-walled stainless steel tank is made of 316L stainless steel, and the outer layer is made of 304 stainless steel. The heat-conducting medium in the temperature-controlled interlayer is food-grade silicone oil, and a vacuum valve is provided at the top of the interlayer.

3. The apparatus according to claim 1, characterized in that, The temperature sensor is a platinum resistance sensor, and the humidity sensor is a capacitive sensor. Both are embedded in the inner tank wall through a sterile seal, and the probe end is in direct contact with the fermentation chamber.

4. The apparatus according to claim 1, characterized in that, The lifting mechanism on the liftable stirring shaft is an electric push rod, which can adjust the turbine blades and the anchor blades within the height range of 1 / 3 to 2 / 3 of the fermentation chamber; the turbine blades are inclined at 30 to 45 degrees, and the edges of the anchor blades are bonded with wear-resistant rubber strips.

5. The apparatus according to claim 1, characterized in that, The spiral heating tube is a seamless stainless steel tube, which is spirally wound around the outer wall of the inner layer of the double-layer stainless steel tank; the cooling coil is a copper corrugated tube, which is attached to the outer side of the spiral heating tube and fixed with cable ties.

6. A method for precise temperature and humidity control of probiotic fermentation based on the device described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Pre-treatment of the device: The double-layer stainless steel tank is cleaned by CIP with the following parameters: pressure 0.8~1.2MPa, temperature 60~80℃, time 15~20 min. A heat transfer medium is introduced and the vacuum is evacuated to -0.06~-0.04 MPa. The parameters are preset by the central control system. S2. Culture medium inoculation: The sterilized culture medium is injected into the fermentation chamber, the volume of the culture medium is 60%~70% of the volume of the fermentation chamber, and activated probiotic liquid is inoculated at an inoculation rate of 5%~8%; S3. Phased control: Activate the central control system to monitor and adjust temperature, humidity and stirring parameters in real time; S4. Fermentation complete: Collect the fermentation broth, centrifuge and freeze-dry it to complete the fermentation.

7. The method according to claim 6, characterized in that, The parameters preset by the central control system in step S1 are as follows: Proliferation period: temperature 37±0.5℃, humidity 60%±2%, stirring speed of the turbine blade 150~200 rpm, height of the turbine blade located at 2 / 3 of the fermentation chamber, and the proliferation period is 0~12 h; Stabilization period: temperature 35±0.5℃, humidity 70%±2%, stirring speed of the turbine blade and the anchor blade is 100~150 rpm, height of the turbine blade and the anchor blade is located at 1 / 2 of the fermentation chamber, and the stabilization period is 12~24 h; Metabolic period: temperature 36±0.5℃, humidity 50%±2%, stirring speed of the anchor blade 50~100 rpm, height of the anchor blade located at 1 / 3 of the fermentation chamber, and metabolic period 24~36 h.

8. The method according to claim 7, characterized in that, In S3, the vacuum degree of the interlayer is -0.06 MPa during the proliferation period and -0.08 MPa during the stationary and metabolic periods; the medium circulation flow rate of the circulation pump is 5~8 L / min.

9. The method according to claim 7, characterized in that, In S3, fermentation gas is released through the exhaust valve every 1.8 to 2.2 hours during the proliferation period, for 28 to 32 seconds each time. During the stable and metabolic periods, fermentation gas is released once every 3.8 to 4.2 hours, for 28 to 32 seconds each time.

10. The method according to claim 6, characterized in that, In step S4, the centrifugation parameters of the fermentation broth are 4000~6000 rpm, 4~8℃, 15~20 min, and the freeze-drying parameters are pre-freezing -40~-50℃, sublimation 20~30℃, desorption 30~40℃, and vacuum degree 10~30 Pa.

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