Drying of foods in order to preserve them during the seasons of abundance for the consumption during the season of shortage is an old art. In India this technique was much widely used in olden days. The traditional dry fruits like kokam ‘Ambapoli’, Manuka and dried mushrooms are eloquent testimony of our ancestors knowledge of dehydration technology. The word dryer, evaporator and dehydrator are at present used as if synonymous therefore at this stage it is essential to clarify the difference between those terminologies. To dehydrate means to remove water by any means, squeezing centrifuging or evaporating. Drying means removal of all possible liquids, water, ether, alcohol etc. from the solids. Evaporation is drying not under well controlled conditions of temperature, humidity and air flow, whereas dehydrator ensures much controlled conditions. In this discussion it is too early to say what degree of controlled conditions.

We are aiming at, hence it is preferred to call the machine a drier rather than a dehydrator or an evaporator. Just as the civil war stimulated the canning industry the Boer War and the First World War stimulated the dehydration industry. To conserve the cargo space enormous amounts of foods were dehydrated during the two world wars. In Germany in 1898 there were 3 drying plants and in 1917 there were 1900. It is this that increased her ability to maintain her food supply during 1939 to 1944. To give an idea of the space conservation may I illustrate with an example. A tonne of apricot in canned form weighs 2800 lbs and in dried form only 400 lbs leaving aside advantages due to the less costly and light packaging. The most economical method of drying is by sundrying and a majority of dried fruits today are sundried.