Food processing: moisturizing and vacuum cooling

Vacuum cooling based on evaporation: when the pressure drops, a portion of the water in the food is boiled at low temperature and removed heat, making the product cool quickly and smoothly.The method is used for bread, leafy vegetables, ripe meat, rice and many high moisture products.

The physical limitations.

To cool to 2–5 °C, the pressure should be lowered to about 7–9 mbar (the slightly saturated pressure of the water at that temperature). The liquid ring pump alone is limited by the steam pressure of the sealing water, approximately 17 mbar at 15 °C, so to reach this level it is usually necessary to combine a Roots or a front ejector, or accept a slower cooling level.

The role of stop.

Most of the absorbed gas is steam. The cold stopper is placed between the vacuum chamber and the steam recovery pump, so that the pump only processes the remaining amount of air.

Request a toilet.

• The pump does not come into direct contact with food but sucks air from the product container chamber, requires a bottle separator and a reverse-flow valve.
• Circulatory sealing water must be cleaned to prevent microorganisms from developing.
• Shredded operation should pump start and stop continuously, need the proper engine and start system.

and other applications.

The legs are no longer used for vacuum tumbling meat and adjustable gas packaging. Each application has its own vacuum and humidity levels, so the suction flow must be recalculated.