indole

roasted nitrogen compound

Found in 496 ingredients across the CompKitchen flavor graph.

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

2D Lewis Structure

Formula: C8H7N
Molecular weight: 117.15 g/mol
PubChem CID: 798 — full record on PubChem

Properties

Odor description: fecal, floral, mothball, animal
Odor threshold — orthonasal, in clean water: 90.0 ppb – 140 ppb median 115 ppb · 2 published values · see all 13 with sources
Volatility: high
CAS number: 120-72-9
Retention index: 1297

Regulatory · United States

FEMA GRAS — Generally Recognized As Safe for flavoring use

✓ Exact match

FEMA number: 2593
GRAS publication: GRAS 3
FEMA primary name: INDOLE

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.

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.

floral, fecal, mothball Flavornet Cas, Flavornet Name, Flavordb Odor Column 3 sources agree

—

animal, burnt, fecal, fishy, floral, honey, jasmine, moth ball, mothball, naphthelene FlavorDB 2.0

432

musky, faecal, cheese FlavorDB 2.0

floral FlavorDB 2.0

floral, jasmine FlavorDB 2.0

fecal, floral, mothball, animal shown above Llm Adjudicated

—

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

13 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

90.0 ppb – 140 ppb

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

Threshold	Matrix	Source	Paper
90.0 ppb SIDA	water	Rychlik 1998 · 1 studies	—
140 ppb	water_odor	Leffingwell	—

In a food matrix

0.660 ppb – 1292 ppb

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

Threshold	Matrix	Source	Paper
0.660 ppb	water (food: tomato)	Literature corpus	28050733
2.6 ppb	water (food: longjing green tea infusion)	Literature corpus	17898464, 17898513, 21750948 +16
3.3 ppb	water (food: unknown)	Literature corpus	21750948, 25763102, 27177033 +10
11.0 ppb	water (food: green tea infusion (jingshan cha))	Literature corpus	17898464, 17898513, 21750948 +16
11.0 ppb	water (food: reference standard (water))	Literature corpus	17898464, 17898513, 21750948 +16
17.0 ppb	water (food: chocolate)	Literature corpus	17898464
31.0 ppb	water (food: soy sauce)	Literature corpus	17898513
1290 ppb	water (food: rum)	Literature corpus	37932358
1292 ppb	water (food: bread)	Literature corpus	41613919
2340 ppb	water (food: fish)	Literature corpus	36950329
Flagged: 167× from the median of this group. Excluded from the range above pending re-check against the source publication — shown rather than hidden.

In air

0.300 ppb

Airborne detection — not comparable to a water threshold.

Threshold	Matrix	Source	Paper
0.300 ppb	air	Nagata 2003	—

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 (31.0 ppb, the engine's canonical value — see the 13 published values). OAV ≥ 1 = perceptible.

Food	Concentration (ppb)	OAV	Source
bread	1292.0	41.7 ⚡	Corpus paper
rum	1291.0	41.6 ⚡	Corpus paper
fish	49.5	1.60	Corpus paper
tomato	0.9	0.03	—
chocolate	0.4	0.01	—
soybean sauce	0.2	0.01	—

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 indole. 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 indole in it. Full concentrations are in the OAV table above.

210 cmpds

254 cmpds

158 cmpds

519 cmpds