“Freeze-drying” food involves the same process as “freezer burn,” referred to in Discussion Question 18.6. For freeze-drying, the food is usually frozen first, and then placed in a vacuum chamber and irradiated with infrared radiation. What is the purpose of the vacuum? The radiation? What advantages might freeze-drying have in comparison to ordinary drying?

Refer to Question Q18.6,

Unwrapped food placed in a freezer experiences dehydration, known as “freezer burn.” Why?