isobutyraldehyde

green aldehyde Key food odorant

Found in 502 ingredients across the CompKitchen flavor graph.

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

2D Lewis Structure

Formula: C4H8O
Molecular weight: 72.11 g/mol
PubChem CID: 6561 — full record on PubChem

Key food odorant (intermediary)

Dunkel et al. 2014

Identified in the meta-analysis of 227 food samples as one of 57 intermediary odorants — appears in 5–25% of foods.

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

Properties

Odor description: malty, green, pungent, aldehydic
Odor threshold — orthonasal, in clean water: 1.0 ppb – 5.9 ppb median 1.2 ppb · 3 published values · see all 16 with sources
Volatility: high
CAS number: 78-84-2

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

2-methyl propanal 2-methyl-propanal 2-methylpropanal

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.

malty, fresh, pungent Flavornet Cas

—

aldehydic, floral, fresh, green, malt, pungent FlavorDB 2.0

460

green- and malt-like FlavorDB 2.0

grassy FlavorDB 2.0

malty, green, pungent, aldehydic 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

16 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

1.0 ppb – 5.9 ppb

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

Threshold	Matrix	Source	Paper
1.0 ppb SIDA	water	Rychlik 1998 · 5 studies	—
1.2 ppb	water_odor	Leffingwell	—
5.9 ppb	water/ethanol 6:4 (food: american bourbon whisky)	Literature corpus	24594176, 33488534, 36144849 +1

In a food matrix

0.490 ppb – 72.0 ppb

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

Threshold	Matrix	Source	Paper
0.490 ppb	water (food: green tea infusion (jingshan cha))	Literature corpus	24594176, 33488534, 36144849 +1
0.490 ppb	water (food: reference standard (water))	Literature corpus	24594176, 33488534, 36144849 +1
0.490 ppb	water (food: longjing green tea infusion)	Literature corpus	24594176, 33488534, 36144849 +1
0.750 ppb	water (food: rice)	Literature corpus	24594176, 33488534, 36144849 +1
1.0 ppb	water (food: extruded wheat flour)	Literature corpus	24594176, 33488534, 36144849 +1
3.0 ppb	water (food: fish)	Literature corpus	24594176, 36144849, 37003052
72.0 ppb	water (food: lamb)	Literature corpus	24594176, 33488534, 36144849 +1
279 ppb	water (food: unknown)	Literature corpus	33488534
Flagged: 319× from the median of this group. Excluded from the range above pending re-check against the source publication — shown rather than hidden.

Retronasal / in-mouth

0.700 ppb – 3.4 ppb

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

Threshold	Matrix	Source	Paper
0.700 ppb SIDA	water_retronasal	Rychlik 1998 · 1 studies	—
3.4 ppb SIDA	oil_retronasal	Rychlik 1998 · 1 studies	—

Other matrix

18.0 ppb – 56.0 ppb

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

Threshold	Matrix	Source	Paper
18.0 ppb SIDA	cellulose	Rychlik 1998 · 1 studies	—
23.2 ppb SIDA	oil_orthonasal	Rychlik 1998 · 2 studies	—
56.0 ppb SIDA	starch	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 (1.0 ppb, the engine's canonical value — see the 16 published values). OAV ≥ 1 = perceptible.

Food	Concentration (ppb)	OAV	Source
flour	20000.0	20000 ⚡	DOI
lamb	530.0	530 ⚡	Corpus paper
lard	300.0	300 ⚡	PMID 25036492
flavoured milk	32.1	32.1 ⚡	Corpus paper
beer	5.1	5.10	Corpus paper
fish	1.0	1.00	—
rice	0.3	0.34	—

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

flour

measured · OAV 20000.0

115 cmpds

457 cmpds

432 cmpds

11 cmpds