Dehydrated food is food that has been preserved by drying. Some dehydrated foods must be rehydrated by adding water before eating or cooking, while others can be eaten dry. Dried milk and milk products, soups, coffee, tea, spices, gelatin, dessert mixes, and pasta are sold in most stores. Other common dehydrated foods include yeast, potatoes, and snack products.
Important features of dehydrated foods are their lightness in weight and their compactness. Over 90 percent of the water is removed during drying. When adequately packaged, most dehydrated foods can be kept for several months if stored below 75 °F (24 °C).
Foods selected for drying must be fresh, clean, and at the proper stage of ripeness. Vegetables are usually blanched (briefly heated and cooled) to destroy enzymes before drying. Such foods as chicken meat and mushrooms are freeze-dried to retain their structure and to aid in rehydration. In the freeze-drying process, the product is frozen and held under conditions of low heat and a nearly perfect vacuum. As a result, the ice in the frozen food is vaporized without melting.
See also Food preservation (Drying).
