The vacuum system evacuates the air contained in the entire vacuum
chamber. This evacuation, causing the drop in pressure inside the
chamber, is what provides the opportunity for the product inside
the chamber to drop in temperature by means of “evaporative
cooling”. “Evaporative cooling” is achieved as the moisture in the
product “boils off” under the reduced pressure inside the vacuum
chamber. The air to be evacuated from the vacuum chamber not only
includes the air surrounding the palletized product but also the
air that is in empty spaces found inside the boxes or cartons of
the product to be cooled.