3-methylindole

roasted nitrogen compound Key food odorant

Found in 30 ingredients across the CompKitchen flavor graph.

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

2D Lewis Structure

Formula: C9H9N
Molecular weight: 131.17 g/mol
PubChem CID: 6736 — full record on PubChem

Key food odorant (individualist)

Dunkel et al. 2014

Identified in the meta-analysis of 227 food samples as one of 151 individualist odorants — appears in <5% of foods, carries the diagnostic signature of specific ingredients.

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

Properties

Odor description: fecal, animal, mothball, civet
Odor threshold — orthonasal, in clean water: 0.016 ppb 1 published value · see all 11 with sources
Volatility: high
CAS number: 83-34-1
Retention index: 1236

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.

Also filed as

skatole

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.

fecal, mothball, jasmine Flavornet Cas

—

animal, civet, fecal, indole, mothball, very strong FlavorDB 2.0

faecal, mothball-like FlavorDB 2.0

animal odour, rancid FlavorDB 2.0

pungent FlavorDB 2.0

skatole 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

11 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

0.016 ppb

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

Threshold	Matrix	Source	Paper
0.016 ppb SIDA	water	Rychlik 1998 · 2 studies	—

In a food matrix

0.130 ppb – 3.8 ppb

Measured in a real food, where the matrix shifts detection — not a clean-water value.

Threshold	Matrix	Source	Paper
0.130 ppb	water (food: reference standard (water))	Literature corpus	36083414
0.410 ppb	water (food: beef vegetable gravy)	Literature corpus	36083414
0.410 ppb	water (food: pork vegetable gravy)	Literature corpus	36083414
0.870 ppb	water (food: longjing green tea infusion)	Literature corpus	36083414
3.8 ppb	water (food: unknown)	Literature corpus	36083414

In air

0.006 ppb

Airborne detection — not comparable to a water threshold.

Threshold	Matrix	Source	Paper
0.006 ppb	air	Nagata 2003	—

Other matrix

2.1 ppb – 32.8 ppb

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

Threshold	Matrix	Source	Paper
0.080 ppb SIDA	mixed_meat	Rychlik 1998 · 1 studies	—
Flagged: 113× from the median of this group. Excluded from the range above pending re-check against the source publication — shown rather than hidden.
2.1 ppb SIDA	buttermilk	Rychlik 1998 · 1 studies	—
16.0 ppb	oil (sunflower oil) (food: cocoa powder)	Literature corpus	36083414
32.8 ppb SIDA	oil_orthonasal	Rychlik 1998 · 2 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.

Where you'd actually smell it

Odor Activity Value = measured concentration ÷ odor threshold (0.41 ppb, the engine's canonical value — see the 11 published values). OAV ≥ 1 = perceptible.

Food	Concentration (ppb)	OAV	Source
back fat	100.0	244 ⚡	Corpus paper

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 3-methylindole. 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 3-methylindole in it. Full concentrations are in the OAV table above.

7 cmpds

8 cmpds

25 cmpds

31 cmpds