Freeze-drying process Freeze-drying (lyophilization) is a process in which a product is dried under low temperature and vacuum. The water in the sample is first frozen into a solid and then directly removed by converting the ice into vapor. This
is done in a vacuum and does not require passing through a
liquid phase. The unique advantage of freeze-drying
is that the sample is stored at a low temperature.
It remains frozen throughout the entire drying process.
It retains its original shape and size while preserving heat-sensitive components (proteins, aromas,
dyes). Dried products have a long shelf life
There is no risk of changes in composition (i.e. enzymatic,
genetic) or infection by microorganisms, i.e.
All this is possible thanks to the lack of water.
In other words, freeze-drying is a dehydration technique. The freeze-drying process differs from other dehydration techniques in that the dehydration takes place while the product is frozen and under vacuum. These conditions stabilize the product and minimize the effects of oxidation and other degradation processes. Freeze-drying became a recognized method of processing heat-sensitive products
when long-term storage at high temperatures
below freezing points is required.
Freeze-drying is widely used in the pharmaceutical industry as well as in other industries,
and is the most expensive unit operation due to its high energy consumption. Conservative lyophilization cycles increase processing times and production costs. Longer lyophilization cycles are often considered suboptimal as they are less reliable and increase the risk of equipment failure. Freeze-drying cycles are mandatory.