Fruit, the sweetness of age, the fishiness of seafood — each is a completely different kind of molecule. People trained in chemistry carry a map that sorts aroma by where it comes from: built by yeast, sleeping in the raw material until fermentation wakes it, born when fats break apart, grown slowly by time. Drink or food, aroma follows the same handful of rules. This is that map, drawn for readers who have never studied chemistry.
Smelling something is the moment a very small molecule, drifting through the air, fits into a sensor deep in your nose. It works like a key in a lock: a different shape fits a different lock, and you perceive a different smell.
Only 3 properties really matter. Hold on to these and the jargon stops being an obstacle.
The lighter and more volatile a molecule, the more easily it rides the air to your nose. Heavy molecules struggle to lift off at all.
Powerful aroma compounds register at nanograms — one billionth of a gram. That minimum line is called the odour threshold.
Some aroma molecules are built by yeast; others lie asleep in the raw material until fermentation wakes them. Each family is born a different way.
Each row is an origin. From top to bottom: built by yeast, woken from the raw material, born when something breaks apart, grown by time, and so on. Every row holds the families born that way, in colour. Fruit, the smell of age, the smells counted as faults, and the smells of food all sit here as equals. Tap a tile to jump to that family.
Two aromas can smell alike and still stand far apart on this map, because they were born differently. That is the backbone of the whole thing.
One descriptor is often shared by compounds from completely different families. Rose belongs both to something yeast builds and to something the plant already held. Mushroom belongs to koji and to shiitake alike. Those overlaps, invisible in a table, appear here as lines. Drag to move, scroll to zoom, touch a node to surface only its connections. Tap a family or compound to jump to its entry.
Node size reflects how many connections it has, so descriptors shared by many compounds grow largest. Zoom with the +/− buttons, the scroll wheel, or a double-click; "Expand" fills the screen (Esc returns).
The deepest difference between families is where the aroma wells up from. Some are assembled from scratch by yeast. Some are seeds already sleeping in the raw material, which fermentation wakes. Some appear when a molecule breaks apart. Some are grown by time. Line them up by origin and it falls into place.
The raw material has no aroma yet. It is born only after passing through the factory called yeast.
The seed is in the raw material from the start — but odourless. Fermentation takes the lid off.
The plant's essential oil is wrapped in sugar and hidden. Fermentation unties the string.
Fats and the like break down or oxidise into aroma molecules — inside the drink, or on the food side.
Builds slowly through chemical change during storage.
Amino acids react with sugars under heat or long storage (the Maillard reaction) — the same route as the char on a dish.
Brought by bacteria or wild yeast that nobody meant to add. Brewing treats them as something to control, but as aroma they can become a signature.
Now the families one at a time, in order of origin. Fruity and non-fruity get equal treatment. Four lines each — key compounds, the character of the molecule, how it forms, and keywords.
The raw material has no aroma yet. It is born only after passing through the factory called yeast.
"The juicy fruit that yeast makes as it ferments" — the lead role in ginjo aroma.
"A round foundation that yeast builds from amino acids" — heavy in excess, thin without it.
The seed is in the raw material from the start — but odourless. Fermentation takes the lid off.
"Tropical notes sleeping in the raw material, woken by fermentation" — overwhelming in trace amounts.
The plant's essential oil is wrapped in sugar and hidden. Fermentation unties the string.
"Florals and lychee the plant already owned" — the main body of essential oils.
Fats and the like break down or oxidise into aroma molecules — inside the drink, or on the food side.
"Green, oily notes born when fat oxidises and snaps" — flavour in traces, a fault as it rises.
"The fishiness a fish gives up as time passes" — add acid and it stops reaching your nose.
Builds slowly through chemical change during storage.
"Peach and coconut, grown by time" — one source of the sweetness of age.
Amino acids react with sugars under heat or long storage (the Maillard reaction) — the same route as the char on a dish.
"Caramel and soy sauce, born where amino acids meet sugar" — the same route as the char on a dish.
Brought by bacteria or wild yeast that nobody meant to add. Brewing treats them as something to control, but as aroma they can become a signature.
"Something in the raw material, rebuilt by an uninvited microbe into smoke" — a deduction at judging, possibly something else at the table.
"Cheese and sweat, left behind by microbes nobody wanted" — the side that gets managed as a fault.
Narrowing to fruity aromas: the same molecules turn up across categories. The tropical note in a Sauvignon Blanc and the one in a tropical IPA are the same thiol. Find where the bottle in front of you sits.
| Drink | Families at work | What you smell |
|---|---|---|
| Ginjo / Daiginjo | Esters | Apple, pineapple, banana (ginjo aroma) |
| Low-polish "juicy" sake |
Esters ＋ Thiols + malic acidity |
Juiciness, tropical notes, fresh acidity |
| Sauvignon Blanc |
Thiols | Passion fruit, grapefruit, blackcurrant bud |
| Tropical IPA (craft beer) |
Thiols ＋ Terpenes | Passion fruit, citrus, florals (from hops) |
| Gewürz- traminer |
Terpenes | Lychee, rose, muscat |
| Muscat wines Imo shochu |
Terpenes | Muscat, florals, citrus |
All 40 compounds across the 10 families. Drink and food aromas share one table. The family cards only name a few key compounds, so this is the only place the actual data lives. The Drink / Food tags say which side the aroma stands on — a compound already in the glass is a different thing from one created when drink meets dish.
"The juicy fruit that yeast makes as it ferments" — the lead role in ginjo aroma.
| Compound | Descriptors | Effect | Threshold | Confidence |
|---|---|---|---|---|
| Ethyl caproateDrink Apple, pineapple |
Apple · Pineapple · Melon At other concentrations, or alongside other compounds, it can read as melon or fully ripe fruit |
＋Builds | — | Reported |
| Isoamyl acetateDrink Banana |
Banana · Pear | ＋Builds | — | Reported |
"Tropical notes sleeping in the raw material, woken by fermentation" — overwhelming in trace amounts.
| Compound | Descriptors | Effect | Threshold | Confidence |
|---|---|---|---|---|
| 3-Mercaptohexan-1-olDrink Grapefruit, passion fruit |
Grapefruit · Passion fruit | ±Swings | 60 ng/LValue from patent WO2010070838A1 — note this is not a peer-reviewed source | Reported |
| 4-Mercapto-4-methylpentan-2-oneDrink Blackcurrant bud |
Blackcurrant bud · Passion fruit Blackcurrant bud or box hedge when low; swings to the unpleasant side when high |
±Swings | 1.2 ng/LDetection threshold in sake (Iizuka et al. 2019); 25 competition samples held 5–14 ng/L | Established |
| 3-Mercaptohexyl acetateDrink Passion fruit, more exuberant still |
Passion fruit | ＋Builds | 4 ng/LFrom patent WO2010070838A1; an order of magnitude below 3MH | Reported |
| Dimethyl trisulfideDrink◆2 Pickled radish |
Pickled radish · Onion | −Fault | 0.18 µg/LThreshold in sake | Established |
| Hydrogen sulfideDrink◆1 Boiled egg |
Boiled egg | −Fault | — | Established |
| MercaptansDrink Onion |
Onion Not a single molecule but a collective name for low-molecular-weight thiols. The source describes them collectively, so we keep them that way. |
−Fault | — | Established |
| Dimethyl sulfideDrinkFood◆2 Nori, corn soup |
Nori, corn soup | ±Swings | — | Established |
"Florals and lychee the plant already owned" — the main body of essential oils.
| Compound | Descriptors | Effect | Threshold | Confidence |
|---|---|---|---|---|
| LinaloolDrink Lily of the valley, citrus |
Lily of the valley, lavender · Citrus · Muscat | ＋Builds | 40 µg/LMeasured in a study of monoterpene alcohols in imo shochu | Reported |
| GeraniolDrink Rose |
Rose · Citrus | ＋Builds | 80 µg/LMeasured in a study of monoterpene alcohols in imo shochu | Reported |
| CitronellolDrink Rose, citrus |
Rose · Citrus | ＋Builds | — | Reported |
| cis-Rose oxideDrink The signature of lychee |
Lychee · Rose | ＋Builds | — | Reported |
"A round foundation that yeast builds from amino acids" — heavy in excess, thin without it.
| Compound | Descriptors | Effect | Threshold | Confidence |
|---|---|---|---|---|
| 2-PhenylethanolDrink Sweet rose and florals |
Rose · Floral | ＋Builds | — | Reported |
| Isoamyl alcoholDrink Precursor to isoamyl acetate |
Never the lead on its own, but shows up as heaviness in quantity |
±Swings | — | Reported |
"Green, oily notes born when fat oxidises and snaps" — flavour in traces, a fault as it rises.
| Compound | Descriptors | Effect | Threshold | Confidence |
|---|---|---|---|---|
| HexanalFood◆1 Cut grass, green leaf |
Fresh-cut grass · Fatty | −Fault | — | Established |
| HeptanalFood◆1 Oily and green |
Fatty · Fresh-cut grass | −Fault | — | Established |
| NonanalFood◆1 Fat, citrus peel |
Fatty · Citrus | −Fault | — | Established |
| DecanalFood◆1 Citrus peel, fat |
Citrus · Fatty | −Fault | — | Established |
| (E,Z)-2,4-HeptadienalFood Fish oil |
Fish oil | −Fault | — | Established |
| 1-Octen-3-oneDrinkFood◆2 Metallic mushroom |
Mushroom · Metallic The very same molecule is a key pleasant aroma in shiitake and part of the fishiness in oxidised fat. |
±Swings | — | Established |
| 1-Octen-3-olDrinkFood◆1 Mushroom |
Mushroom | ±Swings | — | Established |
| DiacetylDrink◆1 Cultured butter, yoghurt |
Butter, yoghurt | ±Swings | 83 µg/LThreshold in sake | Established |
"Peach and coconut, grown by time" — one source of the sweetness of age.
| Compound | Descriptors | Effect | Threshold | Confidence |
|---|---|---|---|---|
| γ-NonalactoneDrink◆1 Sweet honey |
Honey · Coconut | ＋Builds | — | Established |
| γ-DecalactoneDrinkFood◆1 Peach, butter |
Peach · Butter, yoghurt | ＋Builds | — | Established |
| γ-DodecalactoneDrink◆1 Coconut and vanilla sweetness |
Coconut · Vanilla | ＋Builds | — | Established |
| γ-HexalactoneFood◆1 Sweet, leaning fatty |
Coconut | ＋Builds | — | Established |
| γ-UndecalactoneFood◆1 Peach |
Peach | ＋Builds | — | Established |
"Something in the raw material, rebuilt by an uninvited microbe into smoke" — a deduction at judging, possibly something else at the table.
| Compound | Descriptors | Effect | Threshold | Confidence |
|---|---|---|---|---|
| GuaiacolDrinkFood◆1 Medicinal, smoky |
Medicinal · Smoke | ±Swings | 22 µg/LDetection threshold in sake | Established |
| 4-VinylguaiacolDrink◆1 Curry, spice |
Spice, curry · Smoke | ±Swings | 52 µg/LDiscrimination threshold in sake; sake contains 0–350 µg/L | Established |
| 4-EthylguaiacolDrink◆1 Smoked, medicinal |
Smoke · Medicinal | ±Swings | — | Suggestive |
| VanillinDrink◆1 Vanilla |
Vanilla | ＋Builds | 78.9 µg/LDetection threshold in sake | Established |
"Caramel and soy sauce, born where amino acids meet sugar" — the same route as the char on a dish.
| Compound | Descriptors | Effect | Threshold | Confidence |
|---|---|---|---|---|
| SotolonDrink◆1 Caramel, black sugar |
Caramel · Honey | ±Swings | 2.3 µg/LThreshold in sake | Established |
| HEMFDrink◆1 Soy sauce |
Soy sauce · Caramel | ＋Builds | — | Reported |
| FurfuralDrink◆1 Burnt sugar, nuts |
Caramel · Roasted nut | ±Swings | — | Established |
| 3-MethylbutanalDrink◆1 Malt, honey |
Malty · Honey | ±Swings | — | Established |
| MethionalDrinkFood◆2 Cooked potato |
Cooked potato | ±Swings | — | Established |
"Cheese and sweat, left behind by microbes nobody wanted" — the side that gets managed as a fault.
"The fishiness a fish gives up as time passes" — add acid and it stops reaching your nose.
| Compound | Descriptors | Effect | Threshold | Confidence |
|---|---|---|---|---|
| TrimethylamineFood◆1 The fishiness of fish |
Fishy | −Fault | — | Established |