The freeze-drying process is actually a change in water material and its transfer process. A large amount of water containing biological products first frozen into a solid, and then in a vacuum state solid ice directly sublimated into water vapor, water vapor condensate in the condenser into the frost, dry frost after the end of the discharge. In the freeze-dried box to get the required freeze-dried products.

Freeze-dried food will bring you the benefits as follows:

• Maintain food original color, smell, taste, shape and protein, vitamins.

• natural, no preservatives, with excellent preservation capabilities.

• In the package in good condition, has a very long shelf life and a corresponding shelf cycle.

• Can be stored at room temperature, eliminating the need for complex cold chain, which does not require cold storage / refrigerated transport, cold container sales and household refrigerators.

• Food accounts for most of the weight of the water has been removed, so the light weight, easy to transport.

• rehydrated quickly and easily consumed.

• It will give you the ultimate high added value and economic benefits.

 

The freeze-dried products of biological products need to have a certain physical form; uniform color, qualified residual moisture content, good solubility, high survival rate or potency, long shelf life. Therefore, not only the seedling process and the freeze-drying after the preservation of control. More importantly, the freeze-drying process of each stage of the parameters of a comprehensive control in order to get high-quality products. Freeze-drying curve and timing is the basic basis for the freeze-drying process control.
 

Pre-freezing speed
Pre-freezing speed Most machines can not be controlled so that the rate of pre-freezing can only be determined by the pre-freezing temperature and the packing time, and the rate of pre-freezing is required. The freeze-drying box first drops to a reduced temperature before the product Into the box; require the rate of pre-freeze is slow, then the product into the box after the freeze-drying box to cool.
 
Pre-frozen minimum temperature
This temperature depends on the eutectic temperature of the product and the pre-freezing minimum temperature should be lower than the eutectic temperature of the product.
 
Pre-frozen time
The volume of the product is large, the container is not thick at the end of the container, not the product is placed directly on the freeze-drying box layer, and the freeze-drying capacity of the freeze-drying box is poor, and between each board layer and each board layer Part of the machine between the large temperature difference, the requirements of the pre-freezing time longer. In order to freeze all the bottles of the product in the box, it is generally required to maintain a time of 1 to 2 hours after the temperature of the sample reaches a predetermined minimum temperature.
 
Condenser cooling time
Condenser requirements in the pre-freezing period, the pre-freeze has not yet ended, before the vacuum began to cool down. How much time to be determined by the cooling performance of the condenser machine. Requirements in the pre-freeze end of the vacuum when the temperature of the condenser to reach -40 ºC or so. Good machine generally half an hour before the beginning of cooling.
The cooling of the condenser is usually continued from the beginning until the end of the freeze. The temperature should always be below -40 ° C.
 
Vacuum time
Pre-freeze is the beginning of the time to start the vacuum, requiring about half an hour in the vacuum can reach 1 × 10-4 mbar.
Vacuum at the same time, but also freeze-drying box between the vacuum valve to open when the vacuum pump and vacuum valve open the same until the end of the freeze.
 
Pre-freeze the end of the time
The pre-freezing end is the operation of the freeze-drying box freezer, which usually stops the operation of the freezer while evacuating or vacuuming the specified requirements.
 
Start heating time
It is generally believed that the time to start heating (in fact, the vacuum began to sublimate). The start of the heating was achieved after the vacuum reached 1 × 10-1 mbar (close to 1 x 10-1 mm Hg). Some freeze-drying machines were automatically turned on by means of a vacuum relay, i.e., the air level was 1 x 10-1 mbar , Some of the freeze-drying machine is in the vacuum after half an hour to start heating, then the vacuum has reached 1 × 10-1 mbar or even higher.

The total time of freeze drying
The total time of freeze-drying is pre-freezing time, plus the time of sublimation and the second stage of work. The total time is determined and the freeze-drying end time is also determined.
This time according to the product variety, the type of bottle, packing, loading, machine performance, etc. to decide, the general work of a long time in the cold, about 18-24 hours, some special products take a few days time.


Technical Data