Freeze drying process
Freeze dried food need to use vacuum freeze drying technology to dehydrate and dry fresh vegetables. The freeze dryer process is to quickly freeze the moisture into ice, and then sublimate ice into vapor to be removed, so fresh products are dried. According to the freeze dryer process, we know that the equipment must have the ability of quick freezing. It must also have the ability to draw a vacuum. And it has a heating function. Because the sublimating ice needs to absorb heat, an appropriate amount of heat will make the sublimation happen faster.
For example, we process fruits. The freeze dryer process is divided into the following main steps:
1. Prepare fresh fruits, wash them, and then cut them into strips.
2. Put the sliced fruits into the tray, insert the temperature sensor, and prepare for pre-freezing.
3. Quick freeze the fruits in the tray, until the inside of the fruits is completely frozen.
4. Freeze the ice condenser. The function of ice condenser is to collect sublimation water vapor.
5. When the temperature of the vapor condenser reaches lower than minus 40 degrees, start vacuuming.
6. When the vacuum reaches below 50Pa, start to heat the frozen fruits.
In this freeze dryer process, the ice is separated from the fresh fruits step by step, and directly sublimated from the solid into water vapor. At the same time, the water vapor is captured by the vapor condenser and sublimated on the coil. Wait until the product temperature is consistent with the set heating temperature, and the vacuum level reaches the non-load ultimate vacuum level, indicating that the material has been freeze dried. At this moment, you can shut down, release the vacuum, unload the materials, and pack quickly. In this way, a batch of fresh fruits is freeze dried, and the nutrition of the freeze dried fruits will not be lost. The removed water does not take away anything except water.