Freeze dryer referred to as freeze dryer, is the water-containing substances first frozen into a solid state, and then make the water from the solid sublimation into a gaseous state, in order to remove the water and save the substance of the cold drying equipment.
Freeze dryer is generally mainly used to preserve the substance, and maximize the prevention of physical and biological aspects of the dry substance denaturation. The freeze-dried items are easy to store for a long time, and can be restored to the state before freeze-drying and maintain the original biochemical properties after adding water. For heat-sensitive substances such as antimicrobial agents, vaccines, blood products, enzymes and hormones and other biological products, freeze-drying technology can show its superiority.
Two, what is the principle of vacuum freeze dryer
1, the structure of the freeze dryer
The freeze dryer consists of refrigeration system, vacuum system, heating system, electrical instrumentation and control system, the main components for the drying box, condenser, refrigeration unit, vacuum pump, heating/cooling device.
2, the working principle of vacuum freeze dryer
Vacuum freeze dryer mainly uses the principle of sublimation, the items to be dried will be frozen below the temperature of the three-phase point first, and then in the vacuum conditions so that the items in the solid water (ice) sublimation into water vapor directly from the items excluded from the items, so that the items dry. Freeze-drying in a vacuum freeze-dryer is divided into three processes:
(1) Pre-freezing to prepare the sample for the sublimation process that follows.
(2) Primary drying, in which the ice sublimates without melting.
(3) Secondary drying, in which residual moisture bonded to the solid material is removed, leaving a dry sample to complete the freeze-drying.
Three, the characteristics of vacuum freeze dryer
Vacuum freeze dryer freeze drying objects, and sun drying, drying, boiling dry, spray drying and so on, compared to its characteristics are:
1, drying at low temperatures, do not make proteins, microorganisms and so on to produce denaturation or loss of biological vitality. This is particularly suitable for those heat-sensitive substances, such as vaccines, bacteria, poisonous species, blood products and other dry preservation.
2, due to low temperature drying, so that the volatile components of the material and heat denaturation of the loss of nutrients is very small, is a common drying method of chemical products, drugs and food.
3, in the low-temperature drying process, the growth of microorganisms and the role of enzymes almost can not be carried out, can be very good to maintain the original properties of the material.
4, after drying the volume, shape is basically unchanged, the material is sponge-like, no dry shrinkage; rehydration, the contact surface with water is large, and can be quickly restored to the original properties.
5, drying under vacuum, oxygen is very little, so that the oxidizable substances are protected.
6, can remove 95-99% of the water in the substance, the preservation period of the product is long.