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 almost immediately, allowing for earlier shipping and a fresher product.

The boiling point of water at 4.58 mm is 32 degrees Fahrenheit.  The moisture inside the product acts as a heat transfer unit, thus the temperature of the product is the boiling point of the water vapor.  The temperature is thereby controlled by the degree of vacuum obtained and held during the cycle.  The evaporated water is condensed by means of a refrigeration system, and discharged after each cycle.

The rate at which a product can be refrigerated is directly related to the 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 twelve-degree fahrenheit temperature drop.

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. 

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.