Freeze-dried products are quite popular today in Europe and the USA. In Russia, they are just beginning to conquer the market. Nutritionists and supporters of healthy eating declare that these products not only retain all the useful substances of fresh analogues, but are also digested by the body even before they enter the stomach.
How products are sublimated
Sublimation is the physical process of the transition of a substance from a solid to a gaseous state, bypassing the liquid phase. Today, it is fully used to preserve foods with all the nutrients and vitamins for a long time.
The sublimation process was invented by the Russian mining engineer Lappa-Starzhenetsky back in the 20s of the last century. And 40 years later, it began to be used in the manufacture of products for geologists, polar explorers or astronauts.
To sublimate a particular product, it is very quickly cooled to a temperature of about -190 ° C, and then moisture is frozen out of it in special vacuum dryers. Moreover, the higher the freezing rate, the finer the ice crystals formed will be and, consequently, the higher the quality of the sublimated product.
The product obtained as a result of these actions becomes ten times lighter than the original one, and its moisture content does not exceed 8-10%. At the same time, approximately 99% of all vitamins, minerals, enzymes and other biologically active substances are preserved in it, because the sublimation process excludes heat treatment.
Packaging and storage of freeze-dried products
The finished freeze-dried product is placed in a special three-layer package based on aluminum foil, which is filled with nitrogen gas. The last substance, certified in accordance with GOST, instantly evaporates when the package is opened and has absolutely no effect on the quality of the contents. This is why freeze-dried foods do not need to be refrigerated. However, each of them has its own expiration date. Vegetables and berries, for example, are stored for about 2 years, and dairy products for 13 months.
The benefits and harms of freeze-dried foods
Any product can be sublimated today: berries, fruits, vegetables, meat, fish, milk, butter, cereals, juices and even alcoholic beverages. Liquids are sublimated into powder, from which granules are then often formed, and solid products - both into powder and into small pieces.
Due to their light weight, convenient packaging, high content of nutrients and long shelf life without refrigeration, freeze-dried foods are indispensable for hiking or long distance travel. Some of them, such as beet juice, are much more pleasant to take in freeze-dried form than fresh. In this case, it is enough to fill them with the required amount of water.
The higher the water temperature, the faster the freeze-dried products will recover in volume.
The danger of such products for the body may lie in the manufacturer's violation of the sublimation technique or the use of low-quality sources. Only a specialist will be able to correctly determine the quality of the sublimated product.
