Dairy Pasteurizer Sterilization Methods and Maintenance
Pasteurization Methods
Method 1: Low Temperature Long Time (LTLT)
Heat milk to 62-65 deg C and maintain for 30 minutes. This method kills various growth-type pathogenic bacteria in milk with sterilization efficiency reaching 97.3-99.9%. After sterilization, only some thermophilic and heat-resistant bacteria and spores remain. Most are lactic acid bacteria, which are harmless and beneficial to health. LTLT is a batch process, now primarily used by small dairies for producing cheese products.
Method 2: High Temperature Short Time (HTST)
Heat milk to 75-90 deg C and maintain for 15-16 seconds. Shorter sterilization time with higher work efficiency. The basic principle is to kill pathogens. Excessively high temperatures cause more nutrient loss. HTST is a flow process performed in plate heat exchangers, widely used for drinking milk production. Products are not sterile, still contain microorganisms, and require refrigeration.
Flash Pasteurization
Mainly applied in yogurt dairy product production.
Maintenance Procedures
- Equipment managed by dedicated personnel. Monitor refrigeration system operation. Maintain operation records. Stop for inspection if abnormalities found.
- Regularly inspect temperature instruments and valves. Replace damaged valves promptly.
- When not in use for extended periods, clean pipelines thoroughly and drain all accumulated material and water to prevent cold-weather freezing damage, especially water in pumps.
- Inspect tank interior walls for corrosion pits or damage.
- Check whether agitator lacks oil and whether oil seal is intact.
- When winter refrigeration unit stops, drain water from condenser coil to prevent freezing and cracking.
- Before equipment use, clean tank interior with mild hot water, then sterilize with steam. Material enters through fixed pipe. Do not overfill.
- After storage ends, drain remaining material. Rinse promptly with warm water, brush off adhering material. Use 40-50 deg C alkaline solution for comprehensive interior cleaning, followed by clean water rinse.
Operational Standards and Precautions
- Strictly clean and disinfect before liquid material storage.
- After liquid enters the tank, intermittently operate the agitator. Otherwise, cream rises to the surface affecting product quality.
- After material leaves the tank, thoroughly clean all product contact surfaces, pipes, and valves. No dirt should accumulate in dead corners. Exterior should be frequently wiped clean.
- Clean tank surface and inner liner with warm water only. Never use salt water to avoid equipment corrosion.
- Regularly add and replace lubricant in reducer, motor, and bearings.
