What is the process of vacuum cooling
The process of vacuum cooling is the rapid refrigeration of a porous product through moisture removal. Once a product is cut, heat and moisture begin to take their toll. The product will begin to rot from the inside out. When placed in a cold room, the heat is removed in a slow continuous process. However with vacuum cooling the heat is removed very rapidly, allowing for earlier shipping and a fresher product.
After the product is harvested and packaged, it is placed on pallets for shipping. The pallets are loaded into a vacuum tight chamber and the process begins. The equipment drops the pressure inside the vessel by removing air through vacuum pumps. Once the level of vacuum reaches the "flash point" moisture and heat are removed from the product in the form of water vapor. The lower the pressure inside the chamber, the lower the boiling point of water. As the vacuum goes deeper, more water vapor is removed and the product temperature is reduced until the desired temperature is achieved.
The water vapor must be removed in order for the process to work efficiently. The vacuum draws the water vapor past refrigeration coils which condenses the vapor back into water. These two systems allow the process to achieve desired product temperature more rapidly than any other post harvest cooling technique.
The rate at which a product can be refrigerated is directly related to the surface area, density of its tissue and the amount of temperature drop. Typical cooling times range from 20 to 40 minutes at a temperature drop from 80 to 36 degrees Fahrenheit. The average moisture loss is one-percent for each eleven-degree Fahrenheit temperature drop.
Since produce is sold by weight, a hydro-vac system can help reduce moisture loss. This works by spraying clean water over the produce during the vacuum cooling cycle.


What it can do for you
Due to the rapid post harvest refrigeration that vacuum cooling allows, shelf life of the product is extended considerably, thus increasing allowable travel times and opening new markets. Rapidly cooling products will greatly reduce the level of microbiological growth during storage. Vacuum cooling has been documented to have lower levels of microbiological growth than any other cooling method.

Products suitable for vacuum cooling
Vacuum cooling equipment has been used with good results to refrigerate and/or dehydrate many products that will dissipate moisture readily, from fresh vegetables and cut flowers to tobacco and alfalfa. We refrigerate lettuce, cabbage, mushrooms, flowers and Chinese vegetables on a regular basis. Vacuum cooling has been used in the produce industry since the 1950's.

In recent years, the vacuum cooling process has been used in many other industries.

To see how your product will benefit from vacuum cooling click here.