Freeze Drying In Food Processing
Freeze drying in food processing — background
Freeze drying is a special process using freezing to dry materials. In general, the methods of drying the material are carried out at a temperature above 0°C or higher, such as sun drying, spray drying, and vacuum drying. The unique feature of freeze-drying its below-0°C temperature environment. When the product is frozen, the material containing a large amount of water is quickly cooled to about -40°C, and then the moisture inside is directly sublimated into steam under a vacuum environment.
Freeze drying in food processing — food processing
Nutrients are afraid of high temperatures, and the temperature of frying or baking often exceeds 200°C, which can easily lead to the loss of nutrients in the food. Therefore, fried instant noodles and potato chips are called junk food.
Freeze drying in food processing — freeze-drying and food processing
Freeze-drying tech uses the completely opposite idea, using ultra-low temperature for dehydration. First, the food is frozen at a sub-zero temperature, when the internal moisture changes from liquid to solid, it is placed in a vacuum environment. The sharp change in air pressure causes the solid water to directly sublime into a gaseous state, thereby separating it from the food.
The whole process is carried out in a low-temperature and low-pressure environment, so it will not cause protein and other active substances to denature and lose vitality like the high-temperature drying process, nor will the air-drying process cause the food to combine with oxygen in the air and cause an oxidation reaction.
Freeze drying in food processing — benefits of the application of the tech
The benefits of freeze drying in food processing are very obvious:
a. Freeze drying in food processing realizes thorough control of water, 95% of water can be controlled by freeze-drying, theoretically the 95% water in the substance can be extracted.
b. Freeze drying in food processing remains the original shape. A 2 mm thick apple slice is quickly frozen to -40°C, and then 95% of the water in the body is removed. The apple slice is still 2 mm thick and can basically maintain its original shape.
c. Freeze drying in food processing can keep as much nutrition as possible. The quick-freezing method can not only maintain the taste but also maintain nutrition. (Note that the nutrition may be lost or deteriorated after a too-long quick-freezing time).
d. Freeze drying in food processing can ensure no extra additions. The raw materials are directly freeze-dried without any “ingredients” or additions.
e. Freeze drying in food processing guarantees good product taste. After the apple slices and pear slices are freeze-dried, the sugar content is concentrated and becomes sweeter than fresh apples and fresh pears, and is easier to chew and digest. It is suitable for all ages.
f. Freeze drying in food processing can simplify storage and transportation. The weight of a ton of fresh vegetables after freeze-drying is only 100 kilograms, but the volume is basically the same. The truck was originally loaded with a crane, but now it is loaded into a plastic food bag.
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