Page 11 - Use of Geothermal Energy in Food Drying

2.2.8. Freeze Dry ng
Cons der ng the qual ty of the final product, t s one of the best dry ng methods. Freeze dry ng;
It cons sts of freez ng, vacuum, subl mat on and condensat on stages. Th s method s carr ed out
w th the pr nc ple of freez ng the product w th certa n refr gerants, reduc ng the pressure and
transform ng the water from the ce form d rectly nto water vapor w thout melt ng, that s, w thout

turn ng nto water. W th th s method, the hardness of the product s preserved, so there s not much
shr nkage after dry ng and t rega ns ts or g nal form when t s kept n water. In add t on,
the loss of taste and aroma n foods dr ed by th s process s very low. Compared to other dry ng
methods, t has advantages such as rap d water loss, less aroma loss, less chem cal changes,
as well as d sadvantages such as h gh cost and complex techn que. Instant coffees, powdered m lk

and some breakfast cereals are produced by th s method.

P cture 3: Freeze Dryer

3. TYPES OF DRYER
In the ndustr al sense, dry ng s the dry ng process prov ded by the use of electr cal energy

and heat treatment. The actual energy needed s l nked to ach ev ng the appropr ate temperature
to get the energy needed to n t ate the evaporat on process and remove a certa n percentage
of mo sture. The temperature used s ach eved by d rect contact of the a r-dr ed product
(vegetables, fru ts, cereals, etc.) at a relat vely low temperature (35-80°C). In l ne w th th s

nformat on, low-temperature geothermal resources can be cons dered as an energy source for
dry ng agr cultural products.

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