Freeze drying machines use a process called "vacuum freeze-drying" to retain the nutrients in food. This process allows freeze-dried food to maintain its nutritional value, taste, and texture while undergoing dehydration. The following are the key steps and principles for nutrient retention in freeze-drying machines:

1. Rapid freezing

During the freeze-drying process, food is rapidly frozen to very low temperatures, typically between -50 ° C and -80 ° C. This process transforms water into a solid state (ice). The faster the freezing speed, the smaller the ice crystals, which can reduce the damage to cell structure and retain nutrients.

2. Sublimation under vacuum environment

Once the food is frozen, the freeze dryer will place the food in a vacuum environment. Under vacuum conditions, ice sublimates directly from a solid state to a gaseous state through slow heating, without undergoing the transformation of liquid water. This sublimation process removes water from food, but does not damage the cell walls or nutrients in the food.

3. Avoid the influence of high temperature

Traditional drying methods, such as drying or air drying, can cause certain heat sensitive nutrients (such as vitamin C, vitamin B complex, etc.) in food to be destroyed or lost due to high temperatures. However, the freeze-drying process is carried out at extremely low temperatures, avoiding the damage of nutrients caused by high temperatures, especially the preservation of thermosensitive substances.

4. Reduce oxidation and chemical reactions

In a vacuum environment, the moisture in the food is removed and there is very little oxygen, which greatly reduces the occurrence rate of oxidation reactions. Oxidation reaction is one of the main reasons for the loss of food nutrients, especially vitamins and antioxidants. The freeze-drying process ensures the preservation of nutrients for a longer period of time by inhibiting oxidation.

5. Maintain structure and active ingredients

Freeze drying technology preserves the structure of food, so not only are nutrients preserved, but active ingredients such as enzymes, proteins, and anti Yang agents can also be well preserved. This is crucial for certain populations with high nutritional requirements or for the processing of medicinal herbs.

6. Hydrability

Due to the preservation of the cellular structure of food by freeze-drying technology, the food can be well restored to its original form and nutritional value during rehydration (i.e. re adding water to freeze-dried food). This enables nutrients to be absorbed and utilized by the human body.

7. Extend storage time while preserving nutrients

Traditional methods of food preservation, such as pickling, smoking, or high-temperature sterilization, can affect the nutritional content of food. Freeze dried foods can be stored for many years in a dehydrated state, and due to their retention of the vast majority of nutrients, even after prolonged storage, the nutritional value of the food will not significantly decrease.

8. Protect thermosensitive components

Some highly sensitive nutrients, such as vitamin C and polyphenolic compounds, are prone to decomposition under high temperature, light, or oxidative conditions. And freeze-drying machines operate in low temperature and vacuum environments, which can protect these components.

9. Prevent microbial growth

After the water in food is removed, microorganisms such as fungi and molds find it difficult to survive and reproduce in this environment, which reduces the degradation of nutrients. In traditional drying methods, even if food is dehydrated, there will still be residual moisture, which can easily cause the growth of microorganisms and lead to nutrient loss.

10. Maintain anti yang agents and trace elements in food

The freeze-drying process also has a good retention effect on anti yang agents, minerals, and trace elements in food, which is of great significance for ensuring the nutritional value of food, especially for fruits and vegetables that require high anti yang ability retention.

Through these steps, the freeze-drying machine can significantly preserve the nutritional content of food, allowing freeze-dried food to still provide high nutritional value when consumed.