Pasteurization is the process of heating a product to a specific temperature, holding it at that temperature for a set duration, and then rapidly cooling it to eliminate harmful microorganisms.

• In Milk: Pathogenic microorganisms, particularly bacteria like tuberculosis and brucellosis, are destroyed.

• In Fruit Juice: Yeast, mold, and bacteria that cause spoilage are eliminated while minimizing flavor loss.

Key Components of Pasteurizers:

• Steam System: Acts as the heat source. Steam transfers heat to the product via heat exchangers.

• Heat Exchanger: Typically a plate heat exchanger (PHE), responsible for heat transfer to the product.

• Holder System: Keeps the product at the required temperature for a specified time (e.g., 72°C for 15 seconds for milk).

• Balance Tank: Ensures continuous product flow into the system and controls liquid levels.

• Pump Group: Circulates the product and auxiliary liquids (e.g., cleaning water) through the system.

• Control Panel: Automatically monitors and adjusts temperature, pressure, and flow data.

Step-by-Step Operation:

A) Pre-Heating

• The product enters the balance tank.

• A water or product pump transfers it to the heat exchanger.

• In the heat exchanger’s regeneration section, the incoming cold product is pre-heated by the outgoing hot pasteurized product via cross-flow. This heat recovery saves energy.

B) Pasteurization Heating

• The steam system activates.

• Heat is transferred to the product via steam in the heat exchanger.

• The product reaches the target temperature (e.g., 72–85°C for milk, 90–95°C for juice).

C) Holding (Holder System)

• The product is held at the target temperature in a tubular or spiral holder line for a set time.

• This step is critical for complete microbiological inactivation.

D) Cooling

• The hot product re-enters the heat exchanger.

• It is cooled using cold raw product or chilled water for heat recovery.

• The product is typically cooled to 4–8°C before being sent to storage tanks or filling machines.

CIP (Cleaning-In-Place)

Pasteurizers are regularly cleaned using an automated CIP system:

• Chemical detergents, hot water, and sometimes disinfectants are circulated to sterilize the entire system.

Automation & Safety

Modern pasteurizers use sensors to monitor temperature, pressure, and flow rates:

• If the target temperature is not reached, the product is automatically diverted back to the return line, ensuring hygiene.

• All parameters are controlled via a PLC (Programmable Logic Controller) panel.

Industry-Specific Variations:

• Milk: Uses HTST (High-Temperature Short-Time) or UHT (Ultra-High Temperature) pasteurization.

• Fruit Juice: Often uses flash pasteurization (short-time high heat) to minimize vitamin and flavor loss.