The freeze-drying process uses cold temperatures where fresh or cooked foods are flash frozen. Moisture is then removed in a vacuum chamber, as a low-level heat is applied to evaporate ice without returning it to a liquid form. Since the food remains frozen during the process, the food’s cell structures do not change and the products generally retain the original taste and nutritional values.  Almost 100% of the water is removed during the freeze dry process, reducing the food’s weight by about 90%. Freeze-drying is generally more expensive than dehydrating due to the time it takes to complete. Freeze dried food retains the fresh flavors, vitamins, nutrient values, colors, and aromas of the original ingredients. Freeze-dried fruits have antioxidant phytochemicals almost as high as the fresh fruit.

The dehydration process uses hot temperatures and airflow. The heat is applied to the foods between 8 and 10 hours, but even then only about 90% of the moisture is removed from the food.  Dried fruits and vegetables are high in fiber and carbohydrates, neither of which is affected by the dehydration process.