Yogurt Fermentation Tank

An industrial yogurt fermentation tank is a specialized stainless steel vessel designed for the large-scale production of yogurt through controlled fermentation. It provides an optimal environment for the growth of beneficial bacteria such as Lactobacillus bulgaricus and Streptococcus thermophilus, which convert milk into yogurt by producing lactic acid.

The fermentation tank is an ultra-clean tank with a mirror-polished inner surface, which makes it easy to discharge the yogurt, leaving less residue and easy to clean, and the tank is insulated to ensure that the yogurt base is stable at a suitable temperature to complete the fermentation.

The fermentation tank is equipped with a top stirrer, a two-layer large paddle + a bottom small paddle design, a scraper is mounted on the top stirrer, which is convenient for scraping and collecting the remaining yogurt on the tank wall when discharging; In the early stage of milk feeding, the stirrer will rotate at a low speed to ensure that the bacteria are evenly distributed in the yogurt base. When fermentation begins, the stirrer stops rotating; after fermentation is completed, the stirring can be turned on to break the emulsion.

The fermentation tank is equipped with a sterile breathing valve and a sterile air protection device, which can provide positive pressure protection for the product in the fermentation tank to prevent external pollution.

The yogurt discharged from the yogurt fermentation tank can be manually or fully automatically according to customers’ requirements. For small capacities such as 1-2 tons per hour, the manual valves can be used for discharging the material due to the low investment. When for the big capacity like 5-10 tons per hour, the fully automatic valve control technology is adopted, the material is discharged through the valve cluster, and the double-seat double-seal anti-mixing valve is used to avoid cross-contamination between pipelines.

The inner surface weld of the equipment is polished to 320 mesh, and the outer surface weld; the support feet are polished to 240 mesh, and the outer surface uses 2B plate.

The fermentation tank is designed with a cone top and a cone bottom. The cone bottom angle is designed to be 25-45° according to the type of yogurt produced to facilitate the discharge of materials.

The fermentation tank is equipped with a variable frequency speed regulating motor. The tank below 10T is equipped with a central large paddle suspension stirring of 18- 36 rpm/min. The tank of 10 T-50 T can be equipped with side stirring, and the stirring speed is 0- 960 rpm/min variable frequency speed regulation, and the stirring motor is SEW brand.

• Tank body: volume from 500L to 50000L, material contact parts are SUS304 or SUS316L, other tank body parts are SUS304 material, cold rolled stainless steel plate, 2B surface, inner shell 3mm, outer shell 2mm, and the insulation is PU material, thickness is 60mm.
• Agitator: Big paddle agitator+ tank bottom small paddle on the top mounted on scraper, SUS304 or SUS316L material, and polished surface.
• CIP cleaning port: Equipped with spray balls for CIP cleaning, the CIP cleaning port can be designed on the top of the tank or one the side of the tank, and the CIP cleaning port quantity is also customized based on the tank volume.
• Material inlet and outlet: inlet is with a two-piece suit union, outlet is a spiral welded butterfly valve, with pull pod, SMS standard, EPDM seal up.
• Manway: Air-tight top manway, Ø400, silicon rubber sealing ring.
• Aseptic air vent: SUS304 material, clamp connectors, condensate drain pan, condensate was led to the bottom of the tank by a wire hose.
• Tank Leg: 4 adjustable legs, adjustable height is 45mm.
• Operating platform: SUS304, stainless steel patterned plate, centralized drainage, guardrail, ladder.
• Aseptic sampling valve: SUS304, manual sampling, steam sterilization.
• Pneumatic double-seat double-seal anti-mixing seat valve(optional): SUS316L, welded, EPDM sealed, with proximity switch bracket, with leakage chamber, self-cleaning, GEA/INOXPA/SPX/AFLA LAVAL brand.
• Pneumatic butterfly valve: SUS304, welded, EPDM sealed, with proximity switch bracket, Yuanan or Europe Brand.
• Hydrostatic Level Sensor: flange connection, 0~1Bar, with gasket seal, bolt M10×20, PNP three wire system, 4~20mA signal output, with temperature display, IFM/Labom/JUMO/E+H brand.
• Level switch: Baumer/IFM brand.
• Temperature Sensor: PT1000, JUMO brand.

1. Milk Feeding

Pasteurized milk (or yogurt base) is pumped into the fermentation tank. The agitator runs at a low speed to keep the milk evenly mixed and to prevent sedimentation.

2. Culture Inoculation

Live bacterial cultures (Lactobacillus bulgaricus, Streptococcus thermophilus, etc.) are added to the milk. The slow, gentle stirring continues to ensure even distribution of the cultures throughout the yogurt base.

3. Fermentation

The tank’s temperature is precisely maintained at 42–45°C using the insulation system. Stirring is stopped to allow the bacteria to grow and ferment the lactose into lactic acid, forming the desired yogurt texture and acidity. The sterile air system maintains positive pressure to prevent contamination during this critical phase.

4. Cooling & Emulsion Breaking

Once fermentation is complete (usually after 4–6 hours), the tank’s cooling system lowers the temperature to stop bacterial activity. The agitator is briefly restarted to break the yogurt emulsion and ensure a uniform, smooth texture.

5. Discharge

After cooling, the yogurt is discharged through the cone-bottom outlet valve. For fresh cheese or thicker yogurt products, the optional wall scraper helps collect remaining material. Automatic valves ensure a clean and contamination-free transfer to the next processing stage.

6. Cleaning (CIP)

The tank is cleaned using an integrated Clean-in-Place (CIP) system, which sprays cleaning agents and rinsing water inside the tank to ensure it meets hygienic standards for the next production cycle.