History of Food Drying
The preservation of food materials by drying has been carried out since the early recorded history of human civilization. The history of drying foods is a long one and goes back as far as 20 000 BC (Hayashi, 1989). The readers may refer further to Hayashi (1989) for detailed chronological information on the history of food drying. Evidence shows that Middle East and oriental cultures actively dried foods as early as 12 000 BC in the hot sun. During the mesolithic age (around 10 000 BC), fish were caught and dried by people in Solvieux in southern France. In ancient Egypt (around 2800 BC), fruits and nuts (e.g., apples, grapes, apricots, figs, and almonds) were sun-dried. During the middle ages (AD 630 to AD 1630), sun-dried powdered milk was produced by the Mongolian army, while cocoa leaves and fruits were sun-dried in Mexico and Peru. In the late 1700s, the French successfully developed a dehydration unit to dehydrate fruits and vegetables at a controlled temperature.The French team sliced the fruits and vegetables, then dried at hot air (40 C), pressed, and then sealed in tinfoil. However, it was not until the turn of the twentieth century that mechanical drying finally begun to replace natural sun drying. It was particularly at the end of World War II that the mechanical drying has since taken off at great pace. The early methods of drying such as trucked-tray and drum drying were soon improved. This was followed by the developments of new methods (at that time), including spray drying, fluidized bed drying, vacuum drying, and freeze drying. A significant effort continues to the present day to improve these drying methods. In addition, new challenges are constantly emerging as new drying requirements appear for new products. This continues to drive further efforts to develop new, innovative, and novel drying techniques.