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products does not lose biological value, its use does not result in morphological
and histological changes in the body of animals and humans.
Employees of the department of new technologies Scientific - Practical
Center of NAS of Belarus Food and Scientific - practical Center of Hygiene
Ministry of Health of the Republic of Belarus studied the toxicity of the
reference sample of dried carrots and treated with ozone prototype, dried express
- method on Tetrahymena pyriformis. Application of the principle of integrated
assessment showed that both samples are 4 - th class of toxicity (low toxicity).
Fundamentals of vacuum drying. At the interface of two phases "liquid -
vapor" there is an equilibrium flow processes of evaporation and condensation.
Evaporation - the process of converting the liquid into vapor at a rate exceeding
the rate of the reverse phenomenon - condensation. She is a film and dropping.
When liquid condensate wets the film surface and forms a continuous film
thereon, which has a great resistance to heat flow. In the case of dropwise
condensation vapors are deposited on the cooling surface in the condensation
centers in the form of droplets. When condensation drip highest intensity of heat.
To initiate the formation of droplets of the cooling surface is treated with a thin
layer of material which has extremely low wettability with liquid. When there is
a vacuum drying phase transitions 2 "liquid - vapor" and "steam - liquid".
The drying process consists of moving the steam and moisture to the
product surface and evaporation into the environment. In decreasing vacuum
pressure environment in the surface layer of weakening intermolecular bonds
and those molecules whose interaction force is smaller than the other, and torn
diffuse into the medium. When viscous mode they are experiencing many
collisions on the way to the wall of the chamber. Therefore, some of them
returned, contributing to the creation of the boundary layer, the part remains in
space, joining in the association, and some condenses, reaching a wall of the
chamber and giving it the heat of condensation. The wall temperature increases,
some molecules adsorbed on it is reflected again, so the wall can be cooled
intensively. The lower the temperature, the greater the condensation of water
vapor. For active evaporation is necessary that the relative humidity of the
environment is not increased and maintained in accordance with the mode. This
evaporation from the surface of the product causes a rapid decrease in its
humidity to limit hygroscopic. Thereafter, the moisture begins to move to the
surface of the product. According to the thickness of the formed two zones: the
near-surface - and internal diffusion - capillary. As the drying of the diffusion
zone is deepening. As a result of intensive evaporation surface of the product is
rapidly cooled to ambient temperature, the boundary layer is formed, so drying
slows dramatically. To intensify the evaporation process under these conditions,
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