isovaleric acid

sour acid

Found in 202 ingredients across the CompKitchen flavor graph.

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

2D Lewis Structure

Formula: C5H10O2
Molecular weight: 102.13 g/mol
PubChem CID: 10430 — full record on PubChem

Properties

Odor description: cheesy, sweaty, sour, rancid
Odor threshold — orthonasal, in clean water: 410 ppb – 700 ppb median 555 ppb · 2 published values · see all 25 with sources
Volatility: high
CAS number: 503-74-2
Retention index: 840

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

3-methyl butanoic acid 3-methyl-butanoic acid 3-methylbutanoic acid

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.

cheesy, sweaty, sour Flavornet Cas, Flavornet Name, FlavorDB 2.0, Flavordb Odor Column 4 sources agree

acid, animal, cheese, feet, rancid, sour, stinky, sweat, sweaty, tropical FlavorDB 2.0

133

Cheesey, dairy, creamy, fermented, sweet, waxy and berry FlavorDB 2.0

sour FlavorDB 2.0

cheesy, sweaty, sour, rancid 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

25 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

410 ppb – 700 ppb

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

Threshold	Matrix	Source	Paper
410 ppb	water_odor	Leffingwell	—
700 ppb SIDA	water	Rychlik 1998 · 5 studies	—

In a food matrix

12.0 ppb – 1200 ppb

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

Threshold	Matrix	Source	Paper
1.5 ppb	water (food: wine)	Literature corpus	36496598
Flagged: 163× from the median of this group. Excluded from the range above pending re-check against the source publication — shown rather than hidden.
12.0 ppb	water (food: goat milk)	Literature corpus	19753606, 28331124, 36337648 +4
39.0 ppb	water (food: tea)	Literature corpus	19753606, 28331124, 36337648 +4
65.8 ppb	water (food: unknown)	Literature corpus	19753606, 28331124, 36337648 +2
100 ppb	water (food: litsea pungens fruit)	Literature corpus	19753606, 28331124, 36337648 +4
250 ppb	water (food: longjing green tea infusion)	Literature corpus	19753606, 28331124, 36337648 +4
490 ppb	water (food: reference standard (water))	Literature corpus	19753606, 28331124, 36337648 +4
848 ppb	water (food: bread)	Literature corpus	41613919
1200 ppb	water (food: japanese soy sauce)	Literature corpus	19753606, 28331124, 36337648 +4
1200 ppb	water (food: beef vegetable gravy)	Literature corpus	19753606, 28331124, 36337648 +4
1200 ppb	water (food: pork vegetable gravy)	Literature corpus	19753606, 28331124, 36337648 +4

Retronasal / in-mouth

26.0 ppb – 750 ppb

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

Threshold	Matrix	Source	Paper
26.0 ppb SIDA	oil_retronasal	Rychlik 1998 · 1 studies	—
750 ppb SIDA	water_retronasal	Rychlik 1998 · 1 studies	—

In air

0.078 ppb

Airborne detection — not comparable to a water threshold.

Threshold	Matrix	Source	Paper
0.078 ppb	air	Nagata 2003	—

Other matrix

6.0 ppb – 250 ppb

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

Threshold	Matrix	Source	Paper
6.0 ppb SIDA	starch	Rychlik 1998 · 1 studies	—
22.0 ppb SIDA	oil_orthonasal	Rychlik 1998 · 1 studies	—
22.0 ppb	oil (sunflower oil) (food: gouda cheese)	Literature corpus	19753606, 28331124, 36337648 +4
22.0 ppb	oil (sunflower oil) (food: cocoa beans)	Literature corpus	19753606, 28331124, 36337648 +4
22.0 ppb	oil (sunflower oil) (food: cocoa powder)	Literature corpus	19753606, 28331124, 36337648 +4
78.0 ppb	ethanol/water (food: rum / red wine)	Literature corpus	19753606, 28331124, 36337648 +4
78.0 ppb	ethanol/water 40/60 (food: rum (aged))	Literature corpus	19753606, 28331124, 36337648 +4
120 ppb	wine matrix (12% ethanol) (food: rum / red wine)	Literature corpus	19753606, 28331124, 36337648 +4
250 ppb SIDA	cellulose	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.

Where you'd actually smell it

Odor Activity Value = measured concentration ÷ odor threshold (410.0 ppb, the engine's canonical value — see the 25 published values). OAV ≥ 1 = perceptible.

Food	Concentration (ppb)	OAV	Source
jmhj	60501.1	148 ⚡	Corpus paper
cheese	30000.0	73.2 ⚡	Corpus paper
extra virgin olive oil	6000.0	14.6 ⚡	Corpus paper
cocoa	4844.0	11.8 ⚡	Corpus paper
bread	847.0	2.07	Corpus paper
tea	31.0	0.08	Corpus paper
coffee	8.6	0.02	—
wine	8.0	0.02	—

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 isovaleric acid. 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 isovaleric acid in it. Full concentrations are in the OAV table above.

295 cmpds

484 cmpds

210 cmpds

617 cmpds