Figure 1 shows the rise in respiration rates for blueberries and compares this with those of strawberries. The lower respiration rates of blueberries compared to those of strawberries partially accounts for the longer shelf life of blueberries. 1 Field heat should be removed from freshly harvested fruit as soon as possible. The rapid removal of field heat with cold forced air is referred to as precooling or pressure cooling. Conversely, in a conventional refrigerated cool room, removal of field heat is exceedingly slow and inefficient and tightly packed flats of berries may receive inadequate cooling.
Efficient operators combine a precooling setup inside of a refrigerated cold room.
A thermometer should be used to monitor fruit temperature. Experiment with the width of stacks and the width of the plenum to find the most efficient arrangement in terms of temperature reduction and floor space. If fruit is left too long in the forced air tunnel, excessive desiccation can occur. There are other precooling arrangements. After flats have been cooled, they can be left in the cold room until they are packed into market containers.