Drying methods are sun drying, boiling, oven drying, spray drying, and vacuum drying, but ordinary drying methods are usually carried out at temperatures above 0℃. The products dried will shrink the size and harden the texture. Most of the volatile components are lost, some heat-sensitive substances are denatured and deactivated, and some substances are even oxidized. Therefore, the dried product has a large difference in properties compared with that before drying.
The Freeze Dry Machine is basically carried out below 0℃, that is, in the state where the product is frozen, and only when the residual moisture content of the product is lowered in the later stage is the temperature above 0℃, but generally, it does not exceed 40℃. Under vacuum conditions, when the water vapor is directly sublimated, the drug remains in the frozen ice shelf, forming a sponge-like porous structure, so the volume after drying is almost constant. Before using it again, as soon as you add water for injection, it will dissolve immediately. Freeze Dry Machine has some advantages over other machines.
First, many heat-sensitive substances will not be denatured or inactivated.
Second, when dried at low temperatures, some of the volatile components in the material are lost.
Third, during the freeze-drying process, the growth of microorganisms and the action of enzymes cannot work, so that the original traits can be maintained.
Fourth, since it is dried in a frozen state, the volume is almost constant, with the original structure, and concentration does not occur.
Finally, since the moisture in the material exists in the form of ice crystals after pre-freezing, the inorganic salt-soluble substances originally dissolved in water are evenly distributed in the material. During the process of sublimation, the substances dissolved in water are precipitated, which avoids the phenomenon that the inorganic salt carried by the internal moisture migration to the surface in the general drying method is precipitated on the surface to cause surface hardening.
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