Batch Milk Pasteurizer

A batch milk pasteurizer (also known as a vat pasteurizer) is a type of equipment used to pasteurize milk and other liquid food products by heating a batch of the product to a specific temperature and holding it at that temperature for a defined period, followed by rapid cooling. This process aims to destroy pathogenic microorganisms, significantly reduce spoilage organisms, and inactivate certain enzymes, thereby making the product safe for consumption and extending its shelf life. It is distinct from continuous pasteurization methods like HTST (High-Temperature Short-Time).

Types of Batch Milk Pasteurizer

Traditional Vat Pasteurizer: A jacketed vat with a stirrer where milk is heated and held. Can be directly heated by steam or hot water circulated through the jacket.

Open Top Batch Pasteurizer: Simpler designs, often for smaller batches.

Closed Batch Pasteurizer: Fully enclosed, offering better hygiene and preventing atmospheric contamination.

Multi-Purpose Batch Processors: Vats designed not only for pasteurization but also for mixing, cooking, cooling, and blending of various dairy or food products (e.g., ice cream mix, yogurt bases, sauces).

Laboratory Scale Pasteurizers: Small units for research and development or quality control.

Applications in Various Industries:

Dairy Industry: Pasteurization of milk, cream, yogurt base, ice cream mix, flavored milk, and certain cheeses.

Food Processing: Pasteurizing juices, sauces, soups, liquid egg products, honey, and other liquid food ingredients that require gentle heat treatment.

Beverage Industry: Some specialty beverages.

Artisan & Small-Scale Production: Ideal for smaller dairies, craft food producers, or farms producing dairy products for local markets, where continuous flow systems are not economically viable.

Research & Development: Used in food science labs for developing new products and optimizing pasteurization parameters.

Technology:

Jacketed Vessel: The primary design feature, allowing a heating medium (hot water, steam) to circulate around the product vessel for indirect heating.

Agitation System: A slow-speed agitator or stirrer ensures uniform heat distribution throughout the batch, preventing localized overheating and ensuring all particles reach the target temperature.

Temperature Control: Precise temperature sensors (RTDs, thermocouples) and control systems (PID controllers, PLCs) to maintain the required holding temperature for the specified time.

Cooling System: After holding, cold water or a chilled medium is circulated through the jacket to rapidly cool the product.

Chart Recorders/Data Loggers: For documenting temperature and time profiles to ensure regulatory compliance.

Safety Interlocks: To prevent over-pressurization or incorrect operation.

Clean-in-Place (CIP) Capability: Designed for easy and effective automated cleaning.

Material Selection Considerations:

• Product Contact Surfaces (Inner Tank & Agitator): Stainless steel (304 or 316L) is essential. 316L is preferred for its superior corrosion resistance, especially against chlorides found in cleaning agents or certain milk components. Surfaces must be highly polished (e.g., 2B or better sanitary finish) to prevent bacterial adhesion and facilitate cleaning.
• Jacket: Stainless steel (304) or sometimes mild steel (for the outer jacket) with internal stainless steel in contact with the heating medium.
• Insulation: Polyurethane foam, mineral wool, or fiberglass encapsulated within an outer stainless steel shell to minimize heat loss to the environment during heating and holding.
• Seals & Gaskets: Food-grade elastomers like EPDM, silicone, or Viton that can withstand high temperatures and CIP chemicals, ensuring hygienic sealing.
• Pipes & Fittings: Stainless steel (304 or 316L), using sanitary clamps (Tri-Clamp) or welded connections to prevent dead spots and ensure hygiene.
• Agitator Blades: Stainless steel, designed for efficient mixing without damaging the product.