Advantages of freeze-drying: 

(1) Freeze-drying is carried out at low temperatures, making it particularly suitable for many heat-sensitive substances. 

(2) During the freeze-drying process, the growth of microorganisms and the action of enzymes cannot occur. Therefore, the original properties can be maintained. (3) When drying at low temperatures, some volatile components and heat-denatured nutrients in the substance are lost very little. 

(4) Because the drying is carried out under the frozen state, the volume and shape of the product remain almost unchanged, maintaining the original structure and avoiding concentration phenomena. The dried substance is loose and porous, like a sponge, and dissolves quickly and completely when added with water, almost immediately restoring its original properties. 

(5) Under vacuum conditions, the material is in a highly oxygen-deficient state, protecting oxidizable substances. 

(6) Drying can remove 95-99% of the moisture, allowing the dried product to be stored for a long time without deteriorating.