Compounds · Esters · Microbial origin
Isoamyl acetate
Also known as 3-Methylbutyl acetate · Banana oil — an analysis may use any of these names
Ripe banana, sweet, with a candy note. Arrives very fast and spreads far.
- CAS
- 123-92-2
- Formula
- C7H14O2
- Molar mass
- 130.18
- Odour threshold
- 2 ppbin water
- Boiling point
- ≈ 142 °C at atmospheric pressure
This compound boils at 142 °C, so it is lighter than any ordinary essential-oil component. It lies outside the 150–290 °C band, so the marker stops at the left edge — not because that is where it sits, but because the axis does not reach that far.
The two axes are 51 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: Microbial origin — made by bacteria and yeasts, not by plants.
Ethanol, acetic acid and fruity esters are all made by yeasts and bacteria, but the raw material is the plant’s sugar. The microbial pathway is almost always a second layer placed on top of what the plant has made.
About the threshold figure
Low. The banana note is recognisable at very small concentrations.
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
A seven-carbon ester, a small and not very polar molecule, so it boils even lower than limonene. It lies outside the usual essential-oil volatility axis — gone before anything else has had time to open.
Where else you meet it
Ripe banana, jackfruit, young wine, and almost every artificial banana flavour. It is also the alarm pheromone of honeybees.