Precooling
Also known as: field heat removal, rapid cooling
Short definitionRemoving the field heat of harvested fruit and vegetables within a few hours, before they go into storage or onto a vehicle. It slows respiration and water loss and extends shelf life.
Picked produce is alive; it respires, loses water and softens, and the rate of all this multiplies with temperature. For delicate produce such as strawberries, cherries and apricots, every hour that passes after harvest takes roughly a day off the shelf life. Precooling brings the product down to storage temperature in the first hours. Leaving it in a cold room takes one to three days; drawing air through the crates, water showers, vacuum and icing are far quicker.
Precooling is a separate job from storage and needs its own capacity, because all of the product’s heat is pulled out in a few hours; the power needed to store the same product once it is cold is a small fraction of that. The evaporator is chosen with a large surface and a low temperature difference so the product does not dry out. Crates must be vented, and air must pass through the pallet, not around it. Produce such as bananas, tomatoes and cucumbers is not cooled below its own lower limit.