methylbutanoic acid

Found in 3 ingredients across the CompKitchen flavor graph.

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

Properties

Odor description: cheesy, sweaty, sour, rancid
Odor threshold: 490.0 ppb
CAS number: 134-20-3

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.

soy FlavorDB 2.0, Flavordb Odor Column 2 sources agree

pine FlavorDB 2.0, Flavordb Odor Column 2 sources agree

green, cheesy, rancid FlavorDB 2.0, Flavordb Odor Column 2 sources agree

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.

Where you'd actually smell it

Odor Activity Value = measured concentration ÷ odor threshold (490.0 ppb). OAV ≥ 1 = perceptible.

Food	Concentration (ppb)	OAV	Source
coffee	100004.3	204 ⚡	PMID 38204732
cheese	15000.0	30.6 ⚡	Corpus paper
extra virgin olive oil	6000.0	12.2 ⚡	Corpus paper
cocoa	388.0	0.79	Corpus paper

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

Thresholds in published tables

Numbers printed in open-access papers, grouped by the medium the table states. Median and full range of the values; “agree” means two or more papers whose middle 80% of values sit within 100×. Not reviewed.

Medium	Median	Range	Values	Papers	Papers agree?
air	490 µg/L air	0.0018–3.91e+03	12	10	no (6.3 decades)
ethanol solution	1045 ppb	8–2.83e+04	15	13	no (2.5 decades)
food matrix	250 ppb	0.54–1.3e+05	47	36	no (2.3 decades)
model wine or beer	33 ppb	33–33	1	1	one paper
not applicable	33 ppb	33–33	1	1	one paper
oil	22 ppb	9–320	4	3	yes
starch or other	6 ppb	5.5–24	3	3	yes
unstated	137.2 ppb	0.05–5e+04	78	68	no (2.1 decades)
water	490 ppb	1.3–1.8e+03	30	28	yes

Found in

Measured impact first, then profile share

Every ingredient known to contain methylbutanoic 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 methylbutanoic acid in it. Full concentrations are in the OAV table above.

201 cmpds

407 cmpds

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