Drying Techniques

Of modern mechanized drying techniques, the most commonly used is continuous tunnel drying. The food is loaded onto wire mesh trays which are drawn slowly through a long tunnel through which heated air is blown. By the time the food emerges from the far end of the tunnel it is fully dried.

A refinement of the tunnel dryer is the fluidized bed dryer, used for small items such as peas. The food travels along perforated plates through which warm air is blown from below. The air lifts and transports the food while it is drying. The further it goes the hotter the air gets. In the case of peas, moisture content falls from 80 per cent to 50 per cent. The food is then transferred to a stationary drying bin where it is finished off slowly with warm air. Finally, after a total of, say, sixteen hours, the moisture content is down to 5 per cent.