Answer : The practice of freeze-drying foods dates to the ancient Incas, who would set out their crops on the slopes of the Andes, where the foods would freeze and then slowly dry in the low air pressure at high altitude. Modern freeze-drying, which employs a vacuum instead of thin mountain air, was first used for medical products such as blood plasma and for instant coffee. Nescaf, the first popular instant coffee, was introduced in 1938 by Nestl to help Brazil use up a coffee surplus. Nestls freeze-drying process sparked experiments with other foods, including fruit. Because freezedried foods are both long-lasting and lightweight, they proved ideal for feeding astronauts on space missions.
According to research presented at the 2006 American Institute for Cancer Research conference, freeze-dried fruits contain levels of antioxidants almost as high as the fresh originals. Freeze-drying does, however, seem to damage some fragile nutrients. Because freeze-dried fruits typically dont contain added sugar, as many dried fruits do, they can be enjoyed guilt-free, much like fresh fruits.
The USDA Nutrition Database has not computed nutrient values for freeze-dried fruits, but it does contain data on freeze-dried sweet green (bell) peppers. A quarter-cup of freeze-dried peppers- which of course required considerably more volume of fresh peppers to make-has about the same amount of calories and vitamin C as a quarter- cup of fresh peppers; slightly less magnesium, phosphorus and potassium; roughly two-thirds the carbohydrates, total sugars, vitamin A and lutein; and about half the fiber and calcium.