trans-2-nonenal

green aldehyde Key food odorant

Found in 47 ingredients across the CompKitchen flavor graph.

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

2D Lewis Structure

Formula: C9H16O
Molecular weight: 140.22 g/mol
PubChem CID: 5283335 — full record on PubChem

Key food odorant (generalist)

Dunkel et al. 2014

Identified in the meta-analysis of 227 food samples as one of 16 generalist odorants — appears in >25% of foods, typically from generic Maillard, lipid-oxidation, or fermentation pathways.

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

Properties

Odor description: cardboard, fatty, cucumber
Odor threshold — orthonasal, in clean water: 0.150 ppb 1 published value · see all 6 with sources
Volatility: high
CAS number: 18829-56-6

Regulatory · United States

FEMA GRAS — Generally Recognized As Safe for flavoring use

✓ Exact match

FEMA number: 3213
GRAS publication: GRAS 4
FEMA primary name: 2-NONENAL

Use-level matrix not extracted for this substance — check the source publication for current ppm guidance.

Source: FEMA GRAS publications 1-33.

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.

Also filed as

2-nonenal, (e)- e-2-nonenal

Same molecule, unified here — previously counted and displayed as separate compounds.

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.

cardboard, fatty, cucumber shown above Flavornet Cas, Flavornet Name, FlavorDB 2.0, Flavordb Odor Column 4 sources agree

cucumber, fatty, green, melon, paper, waxy FlavorDB 2.0

fermented, fatty, fruity, floral, grassy, woody, sweet, pear FlavorDB 2.0

fatty, green FlavorDB 2.0

fermented, fatty Flavordb Odor Column

—

fruity, floral, grassy, woody, sweet Flavordb Odor Column

—

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

6 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

0.150 ppb

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

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

Retronasal / in-mouth

0.080 ppb – 66.0 ppb

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

Threshold	Matrix	Source	Paper
0.080 ppb SIDA	water_retronasal	Rychlik 1998 · 1 studies	—
66.0 ppb SIDA	oil_retronasal	Rychlik 1998 · 1 studies	—

Other matrix

0.110 ppb – 0.530 ppb

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

Threshold	Matrix	Source	Paper
0.110 ppb SIDA	beer_orthonasal	Rychlik 1998 · 1 studies	—
0.530 ppb SIDA	starch	Rychlik 1998 · 1 studies	—
900 ppb SIDA	oil_orthonasal	Rychlik 1998 · 1 studies	—
Flagged: 1698× from the median of this group. Excluded from the range above pending re-check against the source publication — shown rather than hidden.

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.

Where you'd actually smell it

Odor Activity Value = measured concentration ÷ odor threshold (0.15 ppb, the engine's canonical value — see the 6 published values). OAV ≥ 1 = perceptible.

Food	Concentration (ppb)	OAV	Source
bread	9.0	60.0 ⚡	PMID 38840722

Concentrations from PubMed Central Open Access papers (free literature corpus, MIT-style licensed). Copper = OAV ≥ 10 (strongly perceptible). Green = OAV ≥ 1 (perceptible).

Found in

Measured impact first, then profile share

Every ingredient known to contain trans-2-nonenal. 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-2-nonenal in it. Full concentrations are in the OAV table above.

14 cmpds

17 cmpds

19 cmpds

22 cmpds