A fresh produce comes from the land when it is still warm. To guarantee freshness and a long shelf life of some produce, such as flowers, leafy vegetables and soft fruits, it is important to cool fast. For other produces, like apples and potatoes, fast cooling is less appropriate.
The freezing of agricultural and horticultural goods, like potatoes (fries), vegetables and fruit, but also meat and fish always needs to happen quickly. The reason for this is that slow freezing or temperature fluctuations will allow the water to form large crystals. These large crystals damage the cell structure of the produce. When freezing quickly the crystals remain smal and with it their influence on the produce. This preserves maximum quality and long shelf life.
This will demand quite something of the refrigeration technology. Fast cooling of beans or flowers is done with pre-cool walls, hydro cooling or wet flow-through cooling. Vacuum-cooling is an ideal technique for leafy vegetables, such as spinach or iceberg lettuce and flowers. Freezing fish and meat, but also vegetables is done in freezing tunnels, such as trolley tunnels, belt freezers, block freezers, spiral freezers, fluidised bed freezers, flow freezers and blast freezers.