Reference point
Open a bag of dried shiitake mushrooms and smell at once.
Do this before you read on. An entry only works when you have just smelled the thing.
Rich, earthy, meaty, with an umami layer so clear you can almost taste it. Heavy and lasting.
Fresh and dried shiitake are two different smells in kind. Drying creates a cyclic sulphur compound absent from the fresh mushroom, and that compound makes the characteristic richness. Drying here is not preservation but processing.
The soaking water smells even better than the mushrooms, and cooks know it, which is why they never pour it away.
How to smell it
Smell the dried shiitake in the bag. Soak a few in warm water for twenty minutes and smell the water. The water will be richer than the mushrooms — proof that the aromatic part dissolves in water.
Why this one is hard
Because umami smells are hard to name. People usually say rich or meaty, both borrowed from taste.
Don’t confuse with
This entry
Dried shiitake mushroom
Earthy family
Dried mushrooms have sulphur compounds formed during drying, giving a richness fresh mushrooms entirely lack.
Scientific note
Drying shiitake activates enzymes that break down lentinic acid, producing lenthionine — a cyclic sulphur compound that does not exist in the fresh mushroom. It is the clearest case in the dictionary of preservation actually being processing: drying does not keep the smell as it was but creates an entirely new one.
In Vietnamese life
Dried shiitake is an essential ingredient of many vegetarian dishes and northern feast dishes. Its role is to add depth in place of meat, and it manages that precisely because of the compounds formed during drying.