(E)-2-Decenal
Also written decenal, coriander aldehyde, unsaturated aldehydes
Quick answer
The long-chain aldehyde behind fresh coriander leaf — and behind the fact that a minority of people taste it as soap rather than as citrus.
What it does
Coriander leaf is dominated by a group of unsaturated aldehydes of which (E)-2-decenal is the most prominent, and the same class of compound occurs in some soaps and detergents. That is the mechanism behind the best-known divided opinion in food: for most people the aldehydes read as bright and citric, and for a minority — associated with variation at an olfactory receptor gene cluster — they read as soap. It is a genuine difference in perception rather than a difference in preference, which is worth stating precisely because the usual framing treats it as fussiness.
How it behaves when cooked
Four properties of the molecule, and what they mean at the stove.
- Volatility
- high
- Fat solubility
- moderate
- Water solubility
- low
- Heat stability
- low
Highly volatile and destroyed by heat, which is why coriander leaf is a finishing herb everywhere it is used and why a coriander stirred into a simmering pot contributes colour and nothing else. Crushing or chopping releases the aldehydes and also begins their loss, so the herb is cut at the last moment. Two practical consequences follow. Culantro carries related aldehydes in a leaf tough enough to survive cooking, which is why it can go into a sofrito at the start where coriander cannot. And the same genetic variation applies to both plants — anyone who tastes coriander as soap will taste culantro that way too, which is the useful thing to know before substituting one for the other.
Spices that carry it
Recorded on the compound rather than on each spice, so the two cannot disagree.
- Coriander leafPrincipal component
The compound the whole soap question turns on.
- CulantroMajor component
Related unsaturated aldehydes, in a much tougher leaf. The shared chemistry is why the two smell alike and why the soap perception carries across.
Not to be confused with
Compounds a reader is likely to take for this one, and why they differ.
Linalool
The other major component of coriander leaf aroma, and the floral half of it. Coriander seed is linalool-dominant and carries almost none of the aldehydes, which is the chemical reason leaf and seed taste nothing alike.
Questions this page answers
- why does coriander taste like soap
- why does cilantro taste like soap
- what makes coriander taste soapy
- is the coriander soap thing genetic
- what is decenal