Printed from smellbook.com/smells/onion. This printout keeps the entry for Onion itself: its description, reference card, Connections, questions, evidence, related smells, record details, states, names and citation. It leaves out your own notes, the map, the lists of paths, routes, stories and fragrance directions, and the lists headed “Also linked to” (other entries that share its place or material) and “Linked from”; they are on the page online. The entries this one links to are still printed under Connections and Related smells.
Categories and types group entries for browsing; they are editorial, not evidence. How smells are grouped.
A sharp, pungent and savoury bulb smell that changes dramatically when cut, cooked or browned.
Its type, Source, means the smell is named after “a physical origin that can contribute a smell”; it is not an evidence source, such as a study or a book. The origin page for Onion (the food or drink, not this smell entry) lists every smell recorded as coming from it.
Raw onion is sharp, pungent and savoury, with a stinging edge that reaches the eyes and lingers on the hands. EDITORIAL
Named in the VERIFIED claims about this smell: not a list of what it is made of, and not its cause.
This entry links to
Other entries that link to this one
Links SmellBook records for this entry: what it comes from, where you meet it, molecules, related smells and comparisons. EDITORIAL links are chosen by SmellBook editors and VERIFIED links come from VERIFIED claims. Nothing here is a ranking, and a molecule is not presented as the cause of the smell.
QUESTIONS ABOUT ONION
Raw onion is sharp, pungent and savoury, with a stinging edge that reaches the eyes and lingers on the hands. Once cooked the smell changes markedly: gentle frying makes it softer and sweeter, while browning turns it rich, deep and almost caramel-like. The raw smell clings and is slow to fade. It can be mistaken for garlic or leek, though onion is broader and less pointed.
In SmellBook’s words: pungent, sharp, savoury and sulfurous.
People meet it at the chopping board during kitchen prep, from a frying pan at the start of many meals, and around street food stalls grilling onions. A bag of onions in a cool pantry has a quieter, papery version.
Typical settings: freshly cut onion, frying pan, kitchen prep.
SmellBook links it to one place page: see it in Connections.
One VERIFIED scientific claim from one published source is recorded for this entry: A potent odorant of raw and cooked onion. This claim says only what its source supports, in the scope shown with it.
The scientific study behind this evidence is chemistry or emission work, not a study of how the smell is perceived.
One molecule is named in this claim; see the evidence for the role the claim gives it. The molecule this claim names has only the role the claim states; one molecule is not the whole smell.
Onion is another strong example of preparation transforming smell identity.
SmellBook records one written comparison with other smells: see it in Connections.
No historical source or heritage record is linked to this entry yet.
Answers marked EDITORIAL are written by SmellBook editors to describe the experience and add no scientific fact. Answers marked VERIFIED point to claims on published sources, checked against each source's own summary where one was available (each claim's page says how); what each claim supports is in its own text and scope.
Scientific evidence · 1 claim
A potent odorant of raw and cooked onion
A stable isotope dilution assay found the potent onion odorant 3-mercapto-2-methylpentan-1-ol at 8–32 µg/kg in raw onions and at much higher levels in sliced, stored and then cooked onions, which suggests it forms from precursors produced enzymatically when raw onions are cut.
One potent odorant measured in onions of different origins; it is not a complete account of onion aroma.
How this was found: Odour activity estimate. Compounds were measured and compared with known odour thresholds; nobody smelled this sample to confirm it. Source: primary study; chemistry work.
Michael Granvogl, Monika Christlbauer & Peter Schieberle
Journal of Agricultural and Food Chemistry
DOI 10.1021/jf049874lEach molecule is named by the claim shown after it. This molecule has only the role the claim states; one molecule is not the whole smell. About molecules in SmellBook
Links chosen by SmellBook editors, not a ranking.
Associations can vary strongly by person, place and culture.
PATHS FROM HERE
Each step is a relationship SmellBook editors recorded in the knowledge graph, named as it is published there. Paths are not ranked or personalised, and they do not mean the smells smell alike.
MY SMELLBOOK · LOCAL ONLY
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MAP THIS SMELL
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WHERE THIS SMELL APPEARS
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FOR RESEARCHERS AND EDITORS
Identity, revision history, corrections and how to cite Onion.
CULTURAL: This entry's associations depend on context, language, memory or culture; its description and smell words are editorial. It says nothing about research or historical evidence; evidence for this entry is shown separately: VERIFIED.
A state says how an entry is met, such as wet, aged or roasted. It does not create a new smell, and it adds no scientific fact by itself: states marked EDITORIAL come from the entry's own records, and only those marked VERIFIED are reported by a VERIFIED claim.
How this entry is identified and named, for citing it or matching it with other records.
SmellBook SB-0056 — Onionsmellbook:smell:onionhttps://smellbook.com/smells/onionSmellBook. (2026). Onion (revision 3, 2026-10-06). SmellBook Public Atlas. smellbook:smell:onion. https://smellbook.com/smells/onion@misc{smellbook_onion_r3,
author = {{SmellBook}},
title = {Onion},
year = {2026},
note = {SmellBook Public Atlas, revision 3, 2026-10-06, smellbook:smell:onion},
url = {https://smellbook.com/smells/onion}
}TY - ENCYC ID - smellbook-onion-r3 TI - Onion AU - SmellBook T2 - SmellBook Public Atlas PY - 2026 DA - 2026/10/06 ET - revision 3 UR - https://smellbook.com/smells/onion N1 - SB-0056; smellbook:smell:onion; resolver https://smellbook.com/id/smell/onion ER -
The citation names revision 3 of 2026-10-06, so a reader can tell exactly which version was cited. Citing records what was read; it does not grant a licence.
Onion is another strong example of preparation transforming smell identity.
Other entries whose editors linked to Onion:
Editorial description expanded to answer what it smells like and where you meet it; independently reviewed.
Created 2026-09-22 · Updated 2026-10-06Dataset history In the SmellBook dataset since the first of three dataset releases of 2026-09-30.
No correction notices published for this entry. Corrections policyEVIDENCE MATTERS
SmellBook separates cultural association, community perception, verified evidence, prediction and experimental relationships rather than presenting them as the same thing. Read the evidence guide ↗ See the evidence coverage report ↗