Polygodial
Quick answer
The pungent compound of Tasmanian pepperberry leaf and berry: a heat that arrives late, builds and leaves a numbness, acting through the mustard receptor rather than the chilli one.
What it does
A drimane sesquiterpene dialdehyde, and the principal flavour-active compound of Tasmanian pepper leaf. Its heat is unlike chilli’s or black pepper’s: slow to arrive, rising for some time after the first taste, and followed by a numbing tingle. The reason it feels different is receptor-level — polygodial activates TRPA1, the irritant receptor that mustard oil and cinnamaldehyde act on, and was found in the work establishing this to be selective against TRPV1, the chilli receptor.
How it works
The physiological account, where one is established.
Polygodial’s two aldehyde groups react with the TRPA1 channel on sensory nerves and open it, as other reactive irritants do. In the study that identified the mechanism it activated TRPA1 at sub-micromolar concentrations and left TRPV1, TRPV3, TRPV4 and TRPM8 — the chilli, warm and cold receptors — unaffected. That places pepperberry with mustard and horseradish in receptor terms, although it is not volatile and so does not rise into the nose as they do.
How it behaves when cooked
Four properties of the molecule, and what they mean at the stove.
- Volatility
- low
- Fat solubility
- high
- Water solubility
- low
- Heat stability
- moderate
Not volatile, so pepperberry’s heat stays in the mouth rather than the sinuses, and it is slow to build, which is the practical reason to season with it cautiously and taste after a minute rather than at once. It is fat-soluble and carries well in sauces, dressings and chocolate. Because the leaf’s polygodial content varies considerably between plants, two batches of ground pepperleaf can differ markedly in strength.
Spices that carry it
Recorded on the compound rather than on each spice, so the two cannot disagree.
- Tasmanian pepperberryPrincipal component
Concentrated in the leaf, with the berry also pungent. The same compound gives the New Zealand horopito leaf its heat.
Not to be confused with
Compounds a reader is likely to take for this one, and why they differ.
Piperine
The pungency of black pepper, immediate and clean, through the chilli receptor. Polygodial is slow, numbing and acts on a different receptor; the shared word "pepper" is the only connection.
Allyl isothiocyanate
Mustard and horseradish heat, and the same receptor as polygodial. The difference is volatility: mustard oil reaches the nose and clears in seconds, polygodial stays on the tongue and builds.
Questions this page answers
- why is tasmanian pepper hot
- what is polygodial
- mountain pepper heat