Why Don’t Dried Herbs Have as Much Flavor as Fresh Ones?

Dried herbs have less flavor than fresh ones because most of the volatile oils responsible for their aroma evaporate during drying. These oils are the main components behind an herb’s freshness and are quite sensitive to heat and exposure to air.

Which herbs are more resistant to drying?
Soft-leaved herbs such as basil, parsley, and dill get much of their aroma from fine, delicate oil cells; these cells are easily damaged during drying and lose the oil inside them. That is why dried basil tastes quite muted compared with fresh basil. Woody herbs such as thyme, rosemary, and bay leaf have thicker, more durable oil glands; they retain their aroma much better when dried, and some cooks even prefer them dried in certain recipes because the flavor becomes more concentrated.

How can lost aroma be compensated for?
Although it may seem that a smaller amount of dried herbs is enough compared with fresh ones, the opposite is true: because their aroma is weaker, it is generally necessary to use 3 times as much dried herb as fresh. Adding dried herbs early in cooking helps their oils slowly mix into the dish and release their aroma. Fresh herbs, on the other hand, are generally added at the end of cooking because their aromas dissipate quickly with heat. Storage conditions also directly affect the aroma that remains; dried herbs stored in a closed jar away from light retain their aroma much longer than those left in an open container or on a shelf exposed to light.

Dried herbs also have a limited shelf life: their aroma generally weakens noticeably within six months to one year. The freshness of herbs in a jar that has been open for a long time can be checked by rubbing them between your fingers and smelling them. The drying method also determines how much aroma is retained; freeze-dried herbs preserve much more of their volatile oils than herbs dried with hot air because they are processed at a low temperature. For this reason, the “freeze-dried” label on some products suggests a stronger aroma. Storing herbs as whole leaves and crumbling them just before use is also effective for preserving aroma. Dried herbs that have been crushed into a powder in advance lose their aroma faster than whole leaves because they expose a much larger surface to the air. This is why some cooks prefer to rub dried herbs between their fingers when using them.

The climate and soil where an herb grows also affect its initial oil content; herbs grown in sunny, dry regions generally accumulate more volatile oils, leaving a relatively stronger aroma even after drying. For this reason, dried versions of the same herb from different sources may taste different. Some herbs take on a completely different aroma profile when dried; cilantro is a clear example: fresh cilantro smells sharp and citrusy, while the dried form becomes much duller and more herbal.