Rotundone
Also written (−)-rotundone, alpha-rotundone
Quick answer
The compound that makes black pepper smell peppery — and the same molecule behind the pepper note of Syrah wine. Detectable at a few parts per trillion by most people, and not at all by about one in five.
What it does
A sesquiterpene ketone with a woody, spicy aroma that people identify at once as peppercorn. Black pepper’s other volatiles — pinene, limonene, caryophyllene — give it pine, citrus and wood; rotundone is the part that is specifically pepper. It is extraordinarily potent: the study that identified its role found an odour threshold of about 8 nanograms per litre in water, and about a fifth of the tasting panel could not detect it at any concentration tested, a specific anosmia. Two people grinding the same pepper can therefore genuinely smell different things.
How it behaves when cooked
Four properties of the molecule, and what they mean at the stove.
- Volatility
- moderate
- Fat solubility
- high
- Water solubility
- low
- Heat stability
- moderate
Rotundone is a heavier aroma molecule than the monoterpenes that make up most of pepper’s top notes, so it lingers after the pine and citrus of freshly ground pepper have faded — part of why pepper cooked into a dish still reads as pepper. It is fat-soluble and carries in butter, cream and oil. Because so little is needed to be smelled, grinding pepper at the table rather than cooking it for hours keeps the peppery note at its most vivid, while the pungency of piperine survives either way.
Spices that carry it
Recorded on the compound rather than on each spice, so the two cannot disagree.
- Black pepperMajor component
Present at roughly ten thousand times the level found in the most peppery wines, and the specific peppercorn note of the aroma.
- White pepperContributing component
Retained in the seed after the skin is removed, alongside much reduced monoterpenes.
Not to be confused with
Compounds a reader is likely to take for this one, and why they differ.
Piperine
The two halves of black pepper: piperine is the bite on the tongue, rotundone the smell in the nose. Piperine is not volatile and cannot be smelled; rotundone has no pungency at all.
β-Caryophyllene
Another sesquiterpene of pepper, far more abundant and far weaker — woody and warm rather than specifically peppery.
Questions this page answers
- what makes black pepper smell peppery
- what is rotundone
- rotundone in wine and pepper