Views: 2 Author: Site Editor Publish Time: 2021-12-09 Origin: Site
There are various drying methods, such as sun-drying, boil-drying, drying, spray drying and vacuum drying, etc., but common drying methods are usually carried out at a temperature above 0°C or higher. The dried products generally have the problems of reduced volume and hard texture. Most of the volatile components will be lost. Some heat-sensitive materials will be denatured and deactivated, and some materials may even be oxidized. Therefore, there is a big difference in the properties of the dried product compared to the one before drying. So what are the advantages of freeze drying technology of freeze dryer compared with ordinary drying technology?
1. Many heat-sensitive substances will not undergo denaturation or inactivation, which is collected and sorted by the medical education network.
2. When drying at low temperature, the loss of some volatile components in the substance is very small.
3. During the freeze-drying process, the growth of microorganisms and the action of enzymes cannot proceed, so the original properties can be maintained.
4. Since the drying is carried out in a frozen state, the volume is almost unchanged, the original structure is maintained, and no concentration phenomenon occurs.
5. Since the moisture in the material exists in the form of ice crystals after pre-freezing, the dissolved inorganic salt substances originally dissolved in the water are evenly distributed in the material. During sublimation, the dissolved substances dissolved in the water are precipitated, which avoids the phenomenon of surface hardening caused by the precipitation of inorganic salts on the surface due to the migration of the internal moisture of the material to the surface in the general drying method.
6. The dried material is loose, porous, and sponge-like. After adding water, it dissolves quickly and completely, and restores its original properties almost immediately.
7. Since the drying is carried out under vacuum, there is very little oxygen, so some easily oxidized substances are protected.
8. Drying can remove more than 95% to 99% of moisture, so that the dried product can be stored for a long time without deterioration.
9. Because the material is in a frozen state and the temperature is very low, the temperature of the heat source for heating is not high, and the normal temperature or low temperature heater can meet the requirements. If the freezer compartment and the drying compartment are separated, the drying compartment does not need to be insulated, and there will not be a lot of heat loss, so the use of heat energy is very economical.
Even the best technology has its disadvantages. The main disadvantage of vacuum freeze-drying technology is its high cost. Because it needs vacuum and low temperature conditions, the vacuum freeze dryer must be equipped with a vacuum system and a low temperature system, so the investment cost and operating cost are relatively high.