What is freeze-drying technology?

The vacuum freeze-drying technology is to freeze the food at more than 30 degrees below zero, and then put it into a vacuum Mini freeze dryer machine, and then sublime and dehydrate it to remove most of the water from the food. Of course, the sublimation temperature is relatively low, vacuum + low temperature, which determines that the freeze-drying technology is very friendly to vitamins. Compared with other technologies, freeze-drying technology can reduce the damage of food nutrition, structure and biochemical effects. The color and shape of freeze-dried food are almost unchanged, and the disappearance of water not only makes it difficult for microorganisms to survive on the food, but also prolongs the shelf life of the food, and also greatly reduces the weight, making it more convenient to carry and transport.Contact me,get price:Mini freeze dryer price.

 
Freeze-dried dried fruit is dried fruit made by vacuum freeze-drying technology. Fruits and vegetables provide people with nutrients such as vitamins. In order to extend the shelf life of these foods, people have developed, sun-dried, dried, pickled, and cooked and made into canned fruits, but things like vitamins are , the ability to withstand high temperature is really poor, once it encounters high temperature, it will suffer serious losses. When there is a need, there is creation, so people full of wisdom have developed low-temperature processing technology and vegetable drying oven technology. Therefore, freeze-drying machines are also recognized by more and more people, and the application of freeze-drying machines is becoming more and more extensive soup.
 
Is freeze-dried food safe?
Most people think that freeze-dried fruit is unhealthy, but they are wrong. Freeze-dried fruit is nutritious and harmless. Because the freeze-dried fruit adopts the vacuum freeze-drying method of the freeze-drying machine, the water in the fruit is frozen in advance, and then the frozen water in the fruit is sublimated in a vacuum environment to obtain freeze-dried fruit. Compared with the traditional high-temperature heating, the nutrient loss of fruit chips is relatively small, the nutritional value is much higher, and the original nutrients of the fruit are basically preserved.



In short, the water in the fruit is pumped in a low temperature environment to retain its original nutrition. Not only that, but freeze-dried fruit is durable, lightweight, and easy to carry. Freeze-dried is the best food for home travel or in space (most of the astronauts are freeze-dried products in space), which can satisfy both hunger and stomach. It can also supplement nutrition.
 

Process flow of freeze-drying technology

1. Pretreatment

Different materials to be dried have different pretreatment methods. But in order to obtain a safe and hygienic product, it is necessary to sterilize the freeze-drying equipment. Commonly used disinfection methods are: heat sterilization, gas sterilization and radiation sterilization.
 

2. Vacuum freeze drying (lyophilization)

The vacuum freeze-drying stage is generally divided into a pre-freezing stage, a sublimation drying stage and a desorption drying stage.

Pre-freezing
Pre-freezing is to solidify the free water of the material, giving the dried product the same shape as before drying, preventing irreversible changes such as foaming, shrinking, concentration and solute movement during vacuum drying, and reducing the solubility of the substance due to temperature drop. and changes in the characteristics of material life.
 
Sublimation drying stage
Also known as primary drying, the frozen product is heated in a closed vacuum container, so that the ice crystals sublime into water vapor and escape, thereby dehydrating and drying the product. Drying is gradually pushed inward from the outer surface, and the voids left after the sublimation of the ice crystals become the escape channels for the sublimated water vapor.

Desorption drying stage
Also called secondary drying. After the end of the first stage, there is still a part of water adsorbed on the capillary walls and polar groups of the dry material, which is not frozen. After the second stage of drying, the residual moisture content in the product is generally between 0.5% and 4%.
 

3. Post-processing

Different products have different post-processing methods, and the impact of the environment on the dried products should be minimized. For biological products, it is generally necessary to pack in a vacuum environment or fill the drying chamber with nitrogen and then pack.
 

Freeze Dryer - Did You Pick The Right One?

1. Laboratory typical freeze dryer

The laboratory-type freeze-drying machine is small in size, and has a desktop all-in-one machine and a column type. Desktop all-in-one and column types are available in general-purpose, screw-cap, and multi-manifold types. The volume of the server of the desktop all-in-one freeze-drying machine is small, and the total dry-freezing area is not large. The temperature of the cold trap is generally -50 degrees. Very few use transparent bell-type acrylic drums, which can view the raw materials in the plate. Raw materials are pre-frozen and dull and need to be moved, and there is no temperature control function. Due to the limitation of the indoor space outside the desktop computer, this type of equipment cannot be pre-frozen at -80 degrees. Because of the large external indoor space, the column-type freeze dryer can be pre-frozen at -80, and because the external indoor space is large, the heat removal is good. In this way, the brittleness of refrigeration compressors, control circuits, etc. will be slow.

2. Small-scale freeze dryer:

Generally, there are two types of small-scale freeze dryers. One is to use electric heating as a heating system for heating substances. One is a system that uses silicone oil as a heating material. In terms of appearance design, there are square warehouses and round cabins. At this stage, the Chinese foundation of the round cabin has long been replaced. Because the round cabin cannot be heated by silicone oil, and the total area for drying and freezing is not large. We take the square warehouse freeze dryer as an example to discuss electric heating and silicone oil heating. The cooling of the shelf plate of the electric heating freeze dryer is indirectly derived from the volatile end of the compressor, and the cooling is fast and the temperature is low, during the heating and warming process. Because of the rapid cooling, the cooling and heating are rejected, the temperature control is uneven, and the temperature deviation accounts for a large proportion. Compared with electric heating, the silicone oil freeze dryer is a little more expensive except for the engineering cost, and the effect is complete! The freeze dryer using silicone oil as the material is very stable in cooling and heating, and the temperature can be controlled within 1 degree. It is not easy to damage the raw materials. The real freeze dryer should use silicone oil as the heat transfer medium!
 

3. Consumer freeze dryer:

The construction cost of the consumer freeze dryer is relatively expensive, and the application cost increases, so it is generally used by large enterprises.