The working principle of a food freeze-drying machine is to freeze food at low temperatures, and then use the sublimation phenomenon in a vacuum environment to directly convert solid ice in the food into water vapor and remove it, thereby achieving the purpose of drying. During this process, the temperature of the food is kept below freezing point, effectively preventing the oxidation and degradation of nutrients.

However, food dryers also have some drawbacks. For example, some foods may become harder or chewy after drying, affecting the taste experience. Under high temperature and prolonged drying, some nutrients can be destroyed, reducing their nutritional value. In addition, the purchase cost of food dryers is relatively high, and the usage cost, including electricity bills, needs to be considered.