trans,trans-2,4-nonadienal

green aldehyde Key food odorant

Found in 31 ingredients across the CompKitchen flavor graph.

Look up another compound — search by name, CAS number, PubChem CID, or FEMA #.

2D Lewis Structure

Formula: C9H14O
Molecular weight: 138.21 g/mol
PubChem CID: 5283339 — full record on PubChem

Key food odorant (intermediary)

Dunkel et al. 2014

Identified in the meta-analysis of 227 food samples as one of 57 intermediary odorants — appears in 5–25% of foods.

Source: Angew. Chem. Int. Ed. 2014, 53, 7124–7143

Properties

Odor description: fatty, green, watermelon
Odor threshold — orthonasal, in clean water: 0.090 ppb 1 published value · see all 4 with sources
Volatility: high
CAS number: 5910-87-2

Not in FEMA GRAS publications 1-33. Of 3,367 listed flavoring substances, none match this compound name. May still be food-safe under other regulatory routes (FDA 21 CFR 172, EFSA, JECFA) — check femaflavor.org for the authoritative current list.

How this molecule is described

Sources disagree about odour more often than they disagree about chemistry. Rather than show one answer, here is every description on file with how many ingredient records carry it.

Descriptions on file

Ordered by how many independent descriptor streams give each wording, then by how often it appears. The bar is still replication — one source copied onto many ingredients scores high there — so the two can disagree.

fatty, green, watermelon shown above Flavornet Cas, Flavornet Name, FlavorDB 2.0, Flavordb Odor Column 4 sources agree

fatty FlavorDB 2.0

Bars are the share of ingredient records carrying each description. High agreement means the sources replicate each other — not necessarily that they are right.

Published thresholds

4 measured values from the literature. Grouped by what was actually measured — a threshold smelled in clean water, tasted in the mouth, or measured in a real food are three different quantities and are not pooled.

Orthonasal, in clean water

0.090 ppb

The reference measurement — smelled in water. OAV is computed against this.

Threshold	Matrix	Source	Paper
0.090 ppb SIDA	water	Rychlik 1998 · 1 studies	—

Retronasal / in-mouth

0.060 ppb – 460 ppb

Tasted rather than smelled — a different sense, not comparable.

Threshold	Matrix	Source	Paper
0.060 ppb SIDA	water_retronasal	Rychlik 1998 · 1 studies	—
460 ppb SIDA	oil_retronasal	Rychlik 1998 · 1 studies	—

Other matrix

2500 ppb

Measured in a non-aqueous medium (oil, starch, cellulose).

Threshold	Matrix	Source	Paper
2500 ppb SIDA	oil_orthonasal	Rychlik 1998 · 1 studies	—

Only values we can attribute are listed. Where a compendium's licence does not permit public attribution its figures are omitted here, so every number on this page traces to a citable source.

Found in

Measured impact first, then profile share

Every ingredient known to contain trans,trans-2,4-nonadienal. Ingredients with a measured concentration come first, ranked by odour activity; the rest follow by how large a share of that ingredient's profile this molecule is. The figure beside each is how many different compounds that ingredient has in total — not the concentration of trans,trans-2,4-nonadienal in it.

27 cmpds

44 cmpds

47 cmpds

52 cmpds