In fact, freeze-drying combines the techniques of "freezing," "vacuum," and "drying." The principle involves freezing the substance first and then creating a vacuum. At this point, the moisture present in the substance will directly sublimate from solid ice to a gaseous state and be expelled. This physical process effectively removes a large amount of moisture from the food, reducing the moisture content to below 5%. This prevents the conditions for microbial growth and meets the hygiene and safety standards for shelf-stable food without the need for preservatives. Therefore, freeze-drying is a technology that makes it easier for food to be stored at room temperature for an extended period. Refrigeration or freezing, on the other hand, can lead to moisture absorption and a shortened shelf life.