propionic acid
sour acid Key food odorantFound in 120 ingredients across the CompKitchen flavor graph.
Look up another compound — search by name, CAS number, PubChem CID, or FEMA #.
- Formula
- C3H6O2
- Molecular weight
- 74.08 g/mol
- PubChem CID
- 1032 — full record on PubChem
Key food odorant (individualist)
Dunkel et al. 2014Identified 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.
Properties
- Odor description
- pungent, rancid, soy
- Odor threshold — orthonasal, in clean water
- 11095 ppb – 20000 ppb median 15548 ppb · 2 published values · see all 12 with sources
- Volatility
- high
- CAS number
- 79-09-4
- Retention index
- 1564
FEMA GRAS — Generally Recognized As Safe for flavoring use
- FEMA number
- 2924
- GRAS publication
- GRAS 3
- FEMA primary name
- PROPIONIC ACID
Use-level matrix not extracted for this substance — check the source publication for current ppm guidance.
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.
Same molecule, unified here — previously counted and displayed as separate compounds.
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.
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
12 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
11095 ppb – 20000 ppbThe reference measurement — smelled in water. OAV is computed against this.
| Threshold | Matrix | Source | Paper |
|---|---|---|---|
| 11095 ppb SIDA | water | Rychlik 1998 · 2 studies | — |
| 20000 ppb | water_odor | Leffingwell | — |
In a food matrix
0.920 ppb – 172 ppbMeasured in a real food, where the matrix shifts detection — not a clean-water value.
| Threshold | Matrix | Source | Paper |
|---|---|---|---|
| 0.920 ppb | water (food: cocoa) | Literature corpus | 28331124, 36202886, 39335804 +4 |
| 1.2 ppb | water (food: onion) | Literature corpus | 28331124, 36202886, 39335804 +4 |
| 3.6 ppb | water (food: unknown) | Literature corpus | 28331124, 36202886, 40045612 +3 |
| 3.9 ppb | water (food: bread) | Literature corpus | 28331124, 36202886, 39335804 +4 |
| 10.7 ppb | water (food: pork) | Literature corpus | 28331124, 36202886, 39335804 +4 |
| 162 ppb | water (food: tea) | Literature corpus | 39335804 |
| 172 ppb | water (food: peanut) | Literature corpus | 28331124, 36202886, 39335804 +4 |
| 1535 ppb | water (food: olive oil) | Literature corpus | 28331124, 36202886, 39335804 +4 |
| Flagged: 143× from the median of this group. Excluded from the range above pending re-check against the source publication — shown rather than hidden. | |||
| 20100 ppb | water (food: reference standard (water)) | Literature corpus | 28331124, 36202886, 39335804 +4 |
| Flagged: 1879× from the median of this group. Excluded from the range above pending re-check against the source publication — shown rather than hidden. | |||
In air
5.7 ppbAirborne detection — not comparable to a water threshold.
| Threshold | Matrix | Source | Paper |
|---|---|---|---|
| 5.7 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 (162.0 ppb, the engine's canonical value — see the 12 published values). OAV ≥ 1 = perceptible.
| Food | Concentration (ppb) | OAV | Source |
|---|---|---|---|
| tomato | 38630.0 | 238 ⚡ | DOI |
| honey | 14100.0 | 87.0 ⚡ | PMID 37845313 |
| olive | 13800.0 | 85.2 ⚡ | DOI |
| olive oil | 2885.0 | 17.8 ⚡ | Corpus paper |
| baijiu | 1528.7 | 9.44 | PMID 40415948 |
| milk | 696.0 | 4.30 | Corpus paper |
| peanut | 681.6 | 4.21 | Corpus paper |
| tea | 171.0 | 1.06 | — |
| sage | 40.0 | 0.25 | — |
| bread | 29.3 | 0.18 | — |
| onion | 23.9 | 0.15 | — |
| red wine | 4.0 | 0.02 | — |
| cocoa | 1.0 | 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 shareEvery ingredient known to contain propionic 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 propionic acid in it. Full concentrations are in the OAV table above.
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