The difference between freeze drying and dehydration: Freeze-drying is the sublimation of water, and drying is the evaporation of water. The former is a solid state directly into a gas, the latter is a liquid into a gas.
Vacuum freeze drying is a drying technology that uses the principle of sublimation to dehydrate materials. The rise of freeze-drying technology can better meet people’s needs for green, convenient and nutritious. In addition, the color, aroma, taste and other nutrients in the food can be retained as much as possible, and the shelf life of the food can be effectively prolonged. The process of freeze-drying can be regarded as a process of physical sublimation, which maintains the physical structure of the material to the greatest extent.
Vacuum freeze-drying technology is a new drying method that freezes water-containing materials into solids, and dehydrates materials at low temperature under low temperature and low pressure conditions to achieve drying.
This drying technology protects the original structure and shape of the material to the greatest extent, and finally obtains high-quality dried products.
At present, vacuum freeze-drying technology has been widely used in many fields, especially when this technology is used in food processing to obtain high-quality dehydrated food.
Drying, also known as thermal drying, is a drying process that uses heat carrier and wet carrier to cooperate with each other.
The effect of thermal drying on ingredients is that the temperature goes from outside to inside, the humidity goes from inside to outside, and the speed has a limit. It is the maximum speed of water diffusion from the inside to the outside when the food is at the extreme temperature that it can withstand. If the speed is too high, it will cause the epidermis to shrink and reduce the drying speed; if it is too slow, it will affect the efficiency, and at the same time, if the temperature is too high, it will cause the internal moisture to vaporize too quickly, causing the cells to rupture, resulting in a certain loss of nutrients.
Due to the high temperature, the nutrients in fresh ingredients are easily destroyed, and the taste will also be affected.
What are the advantages of freeze-drying technology?
- Easy to restore by adding water. The lyophilized solid substance can be easily dissolved and recovered after adding water. Compared with other drying methods, freeze-drying technology has unparalleled advantages in maintaining the original physical properties and flavor of the product.
- Protect the activity of heat-sensitive substances, and keep the nutritional value intact. Freeze-drying is generally carried out at low temperature, and the low temperature state is maintained during the sublimation process, so the activity of the substance can be greatly protected, and it is especially suitable for drying such as collagen, vitamins, and probiotics.
- Prevent oxidation and keep it fresh for a long time. The freeze-drying process is carried out under vacuum conditions, so it has a strong protective effect on those substances that are afraid of being oxidized, such as vitamin C, anthocyanin, lycopene, etc.