4 Star Ag Refrigeration, Inc.
Return to Home page
The first link in the cold chain
AG REFRIGERATION SYSTEMS are designed for the special requirements
found in the food industry.  For fresh produce, they generally include
refrigeration applications for pre-cooling, storage, transportation,
distribution and in-store displays.

Crops grown in the field, greenhouses or growing rooms, as is the case
for mushrooms, are subject to ambient temperature, accordingly
containing heat energy called field heat.  The process of removing the field
heat is what is commonly call pre-cooling.  It is the first operation in the
cold chain. The  cold chain consists of all the systems involved in
achieving and maintaining optimum product temperature and for extending
quality and shelf life during production, storage, distribution, marketing up
to the time of consumption.

(agrefrigeration.com is the first "link" in the cold chain)

Pre-cooling methods include :

Vacuum Cooling;

Forced Air Cooling;

Hydro Cooling;

Icing; and

Room Cooling.

Vacuum cooling.  The product is placed in a vacuum so that the
atmospheric pressure around the product is reduced. This reduces the
water vapor pressure around the product, and when the pressure is
lowered below that inside of the product, water evaporates from the
product.  This in turn lowers the surface temperature of the product.

Hydro-cooling.  Cool water is sprayed over the product, or the product is
immersed in cool water.

Forced Air Cooling.   Cold air is "forced" by a fan through the stacked
boxes of vegetables. Because of the increased air flow, the cooling rate is
much faster than with room cooling, so that heat is removed from the

Icing.  This method is applicable only and is only used for product that can
withstand direct contact with ice, such as broccoli.  The ice can be finely
crushed, flaked, or in a slurry with water. Packaging used with icing must
also be able to withstand wetting.

Room Cooling. Product is simply placed in a cooler, and over time, the
product temperature decreases nearly to the cooler temperature. This
process takes a long time.  The longer time it takes to cool it typically
shortens shelf life proportionately.

After pre-cooling, the produce are then transferred to the intermediate
storage area where storage temperatures should be low as possible to
slow product metabolic processes and discourage pathogen growth, but
high enough to avoid freezing or chill injury.