Vacuum Cooling Principles

How Vacuum Cooling Works

Vacuum cooling operates on the principle of evaporative cooling. When the pressure in a sealed chamber is reduced below the saturation pressure of water at the product temperature, water on and within the product begins to evaporate rapidly. This phase change from liquid to vapor requires latent heat (approximately 2,257 kJ/kg of water), which is drawn from the product itself, causing its temperature to drop.

The cooling rate depends on several factors: the vacuum pump's displacement capacity, the product's surface-to-volume ratio, and the water activity of the product. Typically, vacuum cooling achieves a temperature drop from 25°C to 2°C in 20-40 minutes — 6-10x faster than forced-air cooling.

Key Parameters

• Operating vacuum: ≤660 Pa (5 Torr) for produce cooling
• Temperature reduction: up to 25°C per batch
• Weight loss: typically <2% for fresh produce
• Uniformity: ±1°C across the entire batch