Using a Dehydrator to Dry Herbs
Answered by: Conrad Richter
Question from: Daina Lowe
Posted on: July 7, 2001

I have searched and searched for directions on how to dry herbs using a dehydrator. Do you recommend this technique and how long should they be drying? I would appreciate your time in answering this question.

Dehydrators come in different designs operating on different physical principles so it is difficult to provide a definitive answer to your question.

Generally, anything that expels water relatively slowly without expelling too much of the essential oils or otherwise damaging the herb will work fine. A combination of low heat and ventilation works best, so designs that can deliver warm air passing over and through the herbs are what you should look for. The temperature should not be higher than 30 or 35 degrees Celsius (80-90 degrees Fahrenheit). Any higher and you will lose too much the essential oils, which is critical for many of the aromatic herbs such as basil and thyme. Some medicinal herbs which do not owe their activity to volatile principles can be dried a higher temperatures; but as a general rule of thumb, the temperature ranges indicated above will work for most herbs.

For home applications, a simple sweater dryer placed in an airy room of the house works very well. For commercial applications, there are dryers of every size from a small cabinet and up to whole buildings.

We find that it is helpful to strip larger leaves (larger than a thyme leaf) from the stems to stop the inflow of water from the stems. Larger roots should be cut or sliced before drying to increase the surface area from which water can escape.

Some people have had good success with microwave ovens, but we find that microwaves are too harsh and tend to expel too much of the essential oils. Without essential oils, aromatic herbs are no longer aromatic and no longer have much flavour.

Also recommended storage for the dried herbs.

Cool, dry, dark and airtight conditions. Most herbs are best in the first year. Many are still good in the second and third years.

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