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  • Karel Schmiedberger

What does not belong in a freeze-dryer

Updated: Jun 29, 2023

Bomby do lyofilizátoru nepatří!

On these pages we continuously show what and how can be freeze-dried. It will be so good if we show what cannot be lyophilized. At best, such a process can end up with a complete cleaning of the product chamber and shelf system. Worse case scenario means complete destruction of the product.

Never put in a freeze dryer:

Products with closed air

You may have heard on the internet that you can lyophilize a drowned phone from which the lyophilizer sucks the moisture. The truth is that the lyophilizer creates a strong vacuum in the product chamber. The slightest air bubble will expand many times until it bursts. A bubble inside the phone (e.g. under the battery case) can be fatal.


Again, it should be remembered that AMARU is a food freeze-drier. Theoretically, flowers can be put in the freeze-drier and dried, just like herbs. However, the herbs are then ground or blended into small pieces. With flowers, it is desirable to preserve their beauty and our freeze dryer cannot do that because it is designed for maximum speed/aggressiveness of the process. Lyophilization of flowers usually takes 8 - 12 days and is a very gentle process. For this purpose, e.g. VirTis 24DX48 or 36DX66 machines are used.

Products with high sugar content

Honey, condensed milk or chocolate... A brief list of foods that you only put into the machine once and the subsequent cleaning of the entire chamber will discourage you from repeating such an attempt. Sugar, like salt, is very effective in preventing water from freezing. If the product is not well and deeply frozen, meltback occurs - honey or condensed milk starts to boil, even at -20°C. The picture below will give you an idea of exactly what this means.

Pokus o lyofilizaci kondenzovaného mléka

The condensed milk is dried, but who's going to clean it?

Very fatty products

Similar to the effect of high sugar foods, fat is not a friend of drying. In practice, you can freeze-dry fish or various meats, but never try to dry butter, lard or bacon.


Apart from electronics, textiles or chemicals are definitely not suitable for the food freeze dryer.

Live animals

Mainly because it's against the law. Any more complex life form will be killed by the freeze-drying process, which is why cats are more likely to be dried in American microwaves.



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