Traditional sun-drying and hot-air drying are prone to causing material discoloration, significant loss of nutrients, dry and bitter texture, surface browning, and short shelf life. High temperatures and oxygen cause the degradation of natural pigments, loss of heat-sensitive vitamins by 30% to 60%, and trigger Maillard reactions and enzymatic browning, resulting in poor rehydration properties.
A food freeze dryer is the core equipment for modernizing the high-end preservation and drying of food and agricultural products. It freezes the materials at low temperatures and allows ice crystals to directly sublimate in a vacuum environment, completely avoiding high-temperature oxidation. Its core advantages are bright color, a nutritional retention rate of over 95%, crispy texture, pure aroma, no browning phenomenon, and truly achieving the leap from “dehydrated preservation” to “active preservation.”
一．The working principle of the freeze dryer
How a freeze dryer works is a technology that uses the principle of sublimation for drying. It involves rapidly freezing the substance to be dried at a low temperature and then, in an appropriate vacuum environment, allowing the frozen water molecules to directly sublimate into water vapor and escape. The product obtained through freeze drying is called a freeze-dried substance, and this process is called freeze drying.
The substance is always in a low-temperature frozen state before drying, and ice crystals are evenly distributed throughout the substance. The sublimation process does not cause concentration due to dehydration, avoiding side effects such as the formation of foam or oxidation by water vapor. The dried substance has a sponge-like porous structure, with a basically unchanged volume, and is easily soluble in water to restore its original state. To a large extent, it prevents the physical and biological changes of the dried substance.
二．Advantages of the freeze dryer
With the continuous upgrading of the freeze-dried food market, as a manufacturer of professional freeze-drying machines, we have continuously refined our machines based on the actual production scenarios of hundreds of customers. The freeze-drying machines we produce independently possess multiple core advantages.
1. The freeze dryer features an integrated cold trap and drying chamber, giving it a compact and elegant appearance.
2. The entire chamber is made of stainless steel, which complies with food, medicine, and hygiene standards. There is no risk of damage or rusting in the future and no additional costs.
3. The freeze-drying trays are made of aluminum alloy and undergo an anodizing process. The surface is smooth, ensuring more uniform cooling and heating, resulting in better effects and meeting the requirements of aseptic production.
4. The freeze-dried product has a loose and porous structure, resembling a sponge. When added with water, it dissolves rapidly and completely, almost immediately restoring its original shape.
5. The vacuum freeze-drying process is controlled by a computerized automatic system and is completed in one step.
6. A high-power brand compressor is selected, which is technologically mature. It has accumulated rich experience in production and use, and the cooling is rapid.
7. The view window in the freeze-drying area allows for easy observation of the freeze-dried material at any time.
8. The vacuum pump uses a vane pump and a rotary vane pump, and the brand is a benchmark enterprise among domestic counterparts. It is small in size and has high efficiency.
9. The heating system is equipped with a T-type thermocouple that can be inserted into the material to monitor its temperature in real time.
10. The operation screen has a temperature curve graph that can be called up at any time for viewing, allowing for better control of temperature changes.
三．Freeze-Drying Process vs. Air-Drying Process
People have increasingly higher demands for food quality. Traditional methods of drying (such as sun drying and oven drying) can no longer meet the requirements for the taste and nutrition of food. The emergence of freeze-drying machines precisely fulfills these requirements. Let’s compare the differences between the two:
Natural drying/drying: Natural drying uses sunlight and natural wind to evaporate the moisture from the materials. The moisture evaporates slowly from the outside to the inside, resulting in incomplete dehydration. Drying through continuous high-temperature baking destroys the cell structure of the materials, which is a process of forced shrinkage at high temperatures. Both methods directly evaporate the moisture from the liquid state, causing a significant reduction in volume and deformation of the shape. There is no enclosed space, making the materials prone to oxidation and browning, with a significant loss of nutritional components. The material becomes dry and hard in texture, and the taste is poor. The material still retains moisture and has a short shelf life.
Vacuum freeze-drying: In a vacuum environment, ice crystals directly sublime into water vapor without the involvement of liquid water, thus not damaging the cell structure of the materials. The finished product does not deform or crack. It operates in a completely enclosed state, eliminating the risk of oxidation and browning. Under a vacuum and low-temperature condition, the nutritional components of the material are fully retained, the dehydration is thorough, and it can be stored for a long time under normal temperature and moisture-proof conditions.
四．Precautions for The Freeze Dryer
The freeze dryer, as precise refrigeration vacuum equipment, requires standardized operation in daily use, which is also an important factor for stable production. The following are the precautions for using the equipment:
1. Before operating the machine, check that the wiring is correct and the voltage matches.
2. Prior to turning on the machine, inspect all components for loose screws; tighten them immediately if any are loose to prevent equipment malfunction.
3. If unusual noises occur during operation, power off the machine immediately for inspection. Do not attempt to troubleshoot while the machine is running.
4. During operation, do not bring any part of your body close to the rotating positions of the machine.
5. Before drying, first process the product substances simply to make the shapes and sizes consistent and spread them loosely on the metal plate.
6. When freezing the products, generally, the products should be frozen to the set minimum temperature and kept for 1-2 hours. If they are not frozen solid, the samples will crack under the action of vacuum. If the sample is a liquid substance, it will spray out, resulting in the failure of freeze-drying.
7. During freeze-drying of the products, sublimation is the key stage. If the layer plate temperature is set high, the sample will receive more heat, and the sublimation drying time will be shorter; if the layer plate temperature is set low, the sample will receive less heat, and the sublimation time will be longer; if the layer plate temperature is too high, the product will receive excessive heat and rapidly thaw, resulting in freeze-drying failure; if the layer plate temperature is too low, the sample will not receive enough heat, and the sublimation drying time will be prolonged. Therefore, the setting of the layer plate temperature is crucial. It is necessary to observe the color changes of the product substances at any time and adjust the set temperature of the sample chamber at any time.
8. The machine cannot be modified. If modification is needed, notify the manufacturer to check if it is feasible.
五. Summary
buy freeze dryer As a powerful tool for preserving freshness in modern times, they are particularly suitable for the storage of high-value foods and biological products, making them the double winners of quality and time. If you have any questions about freeze-drying machines, feel free to come to us. As a professional manufacturer of freeze-drying machines, Orange Mech will surely provide you with professional answers.
