Compounds · Other compounds · Heat (Maillard reaction and pyrolysis)
Maltol
Also known as Larixinic acid · 3-Hydroxy-2-methyl-4-pyrone — an analysis may use any of these names
Burnt sugar, baked goods.
- CAS
- 118-71-8
- Formula
- C6H6O3
- Molar mass
- 126.11
- Odour threshold
- 9.0 ppmin water
- Boiling point
- ≈ 200 °C estimated
The two axes are 53 points apart. Volatility tells you whether the compound leaves a surface early or late; the threshold tells you how much of it the nose needs before it notices. When the two sit this far apart, they explain things the percentages on an analysis cannot explain on their own.
Where it comes from
Biosynthetic pathway: Heat (Maillard reaction and pyrolysis) — fire breaks large molecules into ones you can smell.
About the threshold figure
High. Maltol needs large amounts, and in industry it is used at parts per million, not parts per billion.
Published thresholds differ by several orders of magnitude, because of differences in measuring method, sample purity and panel. The figure here is an order of magnitude for relative comparison, not a measurement. We give it only for compounds where the literature broadly agrees — 52 of the 106 compounds in the library. The rest are left blank rather than guessed.
Why it sits where it does
Maltol is a small pyrone ring carrying both a hydroxyl and a ketone group. Two polar groups on a six-carbon skeleton make it bind tightly to itself in the solid state — it sublimes and decomposes before it can boil. So it does not leave a surface as quickly as its small molecular mass suggests.
Where else you meet it
It forms when sugar is heated to a moderate temperature: bread crust, malt, lightly roasted coffee, and dark beer. It is also used in the food industry to enhance sweetness without adding sugar.
Dictionary entries that mention this compound
About the boiling-point figure
Maltol sublimes and decomposes before boiling at atmospheric pressure, so it has no measurable boiling point in the ordinary sense. The value here is an estimate used to place it on the volatility axis, not a measurement. Why this detail matters