Spice compounds
What these are
62 compounds that between them account for most of what the spices in this catalogue smell, taste and look like. Each page answers three questions: what the compound does to a person, how it behaves in a pan, and which spices carry it.
The second of those is the reason these pages exist. Whether a compound is volatile, whether it dissolves in fat or in water, and whether it survives heat are between them the explanation for almost every rule about when a spice goes into a dish — and they are properties of the molecule, not of the spice, so they can only be explained once rather than a hundred and fourteen times.
Capsaicinoid
Capsaicin
The compound that makes chillies hot, and the reason chilli heat behaves so unlike every other pungency in the spice cupboard: it is oily, it does not evaporate, and ordinary cooking removes only a part of it.
31 spicesDihydrocapsaicin
The second of the two compounds that make a chilli hot: capsaicin with one double bond removed, present in every hot pepper beside it and, in some, the larger share of the heat.
28 spices
Alkaloid
Alkylamide
Hydroxy-α-sanshool
The compound behind the buzzing, numbing tingle of Sichuan pepper and sanshō — not a heat at all, but a vibration, and the clearest demonstration that pungency is several unrelated phenomena.
3 spicesSpilanthol
The alkylamide that makes jambu buzz and numb the mouth — a structural relative of the sanshools in Sichuan pepper, and not the same compound.
1 spice
Organosulfur compound
Allyl isothiocyanate
The volatile sulfur compound behind mustard, horseradish and wasabi — a pungency that goes up the nose rather than into the tongue, and that does not exist until the plant is damaged.
4 spicesAllicin
The compound responsible for the smell of cut raw garlic — which does not exist in the intact clove, forms within seconds of cutting, and has largely decomposed again within minutes.
2 spicesDiallyl disulfide
The garlic smell that remains once allicin has broken down — the aroma of cooked garlic, garlic oil and garlic breath rather than the sharp bite of garlic freshly crushed.
2 spicesAlliin
The odourless sulphur amino acid that an intact garlic clove or ramsons leaf stores in place of a smell, and that becomes allicin within moments of the tissue being cut.
2 spices4-Hydroxybenzyl isothiocyanate
The pungent compound of white and yellow mustard seed, released from sinalbin when the seed is wetted and crushed: an oily, mildly irritant heat that stays on the tongue, and that water destroys within minutes at a neutral pH.
1 spicePropanethial S-oxide
The small volatile sulphur compound that makes the eyes water when an onion is cut: absent from the whole bulb, and made within moments of cutting by two enzymes working in sequence.
1 spice
Phenylpropanoid
Cinnamaldehyde
The compound that smells of cinnamon, and the great majority of what is in cinnamon bark oil — which is why the two cinnamons taste alike and differ in almost everything else.
5 spicesEugenol
The smell of cloves, and the compound that carries a genuine local anaesthetic effect — the reason a clove held against a sore tooth is a practice found in a dozen unconnected traditions.
9 spicesRegulatedAnethole
The compound that makes aniseed, fennel and star anise smell alike despite belonging to three unrelated plant families — one of the clearest cases in cooking of chemistry cutting across botany.
7 spicesEstragole
Anethole’s isomer: the same formula rearranged, smelling greener and more herbal, and — unlike anethole — the subject of a regulatory assessment that is routinely misreported as a warning about eating fennel.
8 spicesRegulatedSafrole
The principal aromatic of sassafras root bark, prohibited as a food ingredient in the United States — and the reason filé powder, made from the leaf, remains perfectly legal.
2 spicesRegulatedMyristicin
The compound behind nutmeg’s warm, slightly narcotic smell, and the one responsible for the genuine and thoroughly unpleasant toxicity of nutmeg taken in quantity.
4 spicesRegulatedMethyl cinnamate
The sweet, fruity, strawberry-and-balsam aroma compound that makes up almost all of strawberry gum’s leaf oil and half of ishpingo’s — and the reason ishpingo tastes sweeter than the cinnamon it is sold as.
2 spices
Phenolic
Gingerol
The pungent compound of fresh ginger, and the reason dried ginger is not simply fresh ginger with the water removed: drying converts it into a different, sharper compound.
1 spiceVanillin
The principal aroma compound of vanilla, and the most-produced flavour compound in the world — which is why "natural vanilla" and "vanilla flavour" is a real distinction and a smaller one than most people assume.
1 spiceThymol
The sharp, medicinal phenol of thyme, oregano and ajwain — and, with its isomer carvacrol, the compound that decides which of those a herb tastes like.
9 spicesCarvacrol
Thymol’s isomer, and the compound that makes oregano taste of oregano — the two are the same atoms differently arranged, and the ratio between them is what separates two herbs that grow side by side.
8 spicesCuminaldehyde
The compound that makes cumin smell of cumin — pungent, green and sweat-adjacent, and unmistakable in a quantity far below what most other aromatics need.
2 spicesGuaiacol
The phenol that smells of smoke — produced when the lignin in wood breaks down under heat, and the reason a fire-dried spice tastes of the fire rather than of itself.
6 spicesSyringol
The other wood-smoke phenol, and the one closest to what people mean by the smell of smoked food. It comes from the hardwood part of lignin, which is why the choice of wood is a specification rather than a preference.
5 spicesShogaol
The pungent compound that gingerol becomes when ginger is dried or heated, and the reason dried ground ginger is sharper, hotter and less fresh than the root it came from.
1 spice4-Methylphenol
A faecal, horse-stable smelling phenol that forms when white pepper is retted, and one of the two compounds most responsible for the off-odour of poor white pepper.
1 spiceGlucovanillin
Vanillin bound to a sugar: the form in which a green vanilla pod holds its flavour, odourless until curing frees the vanillin.
1 spice
Lactone
Coumarin
The sweet hay-and-vanilla smell of new-mown grass, tonka bean and cassia — and the compound behind the single most-repeated and most-garbled piece of spice safety advice in circulation.
6 spicesRegulatedSotolon
The compound that smells of maple syrup, fenugreek and aged wine at once — extraordinarily potent, and detectable at concentrations lower than almost anything else in food.
4 spices
Monoterpene
Limonene
The citrus-peel terpene, and the most widespread aroma compound in the spice cupboard — present in eight spices in this catalogue that a reader would never describe as citrusy.
28 spicesp-Cymene
A dry, woody, faintly solvent-like terpene that sits under cumin, oregano and nigella — rarely the point of a spice, and often the reason an old one smells harsh.
12 spicesSabinene
The peppery-pine terpene that sits under nutmeg, mace and several aromatic leaves — the fresh top note that a pre-ground spice has already lost.
10 spicesα-Pinene
The smell of pine forest and of gin — the most widely distributed terpene in the plant kingdom, and the compound that makes juniper taste like the outdoors.
11 spicesγ-Terpinene
A mild, faintly citrus terpene that matters less for what it smells of than for what it turns into: p-cymene, which is why an ageing spice grows harsh rather than merely faint.
11 spicesAscaridole
The camphorous, faintly petroleum-like compound that defines epazote — an organic peroxide, unusual among culinary aromatics, and the reason the herb is both distinctive and dose-limited.
1 spice
Oxygenated monoterpenoid
Linalool
The floral, faintly citrus terpenoid found in more spices in this catalogue than any other single aroma compound — and the reason coriander leaf and coriander seed, from one plant, smell like different ingredients.
18 spices1,8-Cineole
The eucalyptus-and-camphor note found in ten spices here — the compound that makes cardamom cooling, rosemary medicinal, and bay leaf recognisable in a stock you cannot see it in.
14 spicesCarvone
The compound that exists in two mirror-image forms smelling of caraway and of spearmint respectively — the cleanest demonstration in food that the nose detects shape, not composition.
4 spicesCamphor
The heavy, penetrating, medicinal note that lurks behind rosemary, sage and lavender — the compound responsible for the moment a herb tips from aromatic to soapy.
4 spicesCitral
The compound that smells of lemon without being from a lemon — the reason lemongrass, some basils and fresh ginger share a citrus note that none of them gets from citrus.
5 spicesα-Terpinyl acetate
The sweet, faintly floral ester that sits alongside cineole in cardamom — the half of the smell that a pre-ground pod loses first, leaving the cooling half behind.
3 spicesSafranal
The principal aroma compound of dried saffron — hay-like, honeyed and faintly metallic — and one that barely exists in the fresh flower. It is made during drying, from picrocrocin.
1 spiceMenthol
The cooling compound of peppermint. It feels cold because it opens the same receptor that low temperature does, not because it lowers the temperature of anything.
1 spiceThymoquinone
The main constituent of the essential oil of nigella seed, falling as the seed is roasted and quickly destroyed by light; how much of nigella’s smell it accounts for has not been measured.
1 spice
Sesquiterpene
β-Caryophyllene
The peppery, woody sesquiterpene that gives black pepper, cloves and allspice a common warmth — larger and heavier than the monoterpenes, and correspondingly harder to lose.
7 spicesZingiberene
The sesquiterpene that smells of ginger — the aroma half of the rhizome, entirely separate from the pungency half, and the part that disappears in a long braise.
2 spicesRotundone
The compound that makes black pepper smell peppery — and the same molecule behind the pepper note of Syrah wine. Detectable at a few parts per trillion by most people, and not at all by about one in five.
2 spicesPolygodial
The pungent compound of Tasmanian pepperberry leaf and berry: a heat that arrives late, builds and leaves a numbness, acting through the mustard receptor rather than the chilli one.
1 spice
Polyphenol
Curcumin
The yellow pigment of turmeric, the most-studied compound in the spice cupboard, and the clearest case anywhere of laboratory findings being reported as though they were clinical ones.
1 spiceAnthocyanins
The red-to-purple-to-blue pigment family, and the only colour in this catalogue that changes with acidity — which is why a shiso pickle turns scarlet and a red cabbage turns blue.
5 spices
Carotenoid
Capsanthin
The red carotenoid of ripe peppers — the reason paprika, Kashmiri chilli and gochugaru are bought for their colour, and the reason they must be kept in the dark.
17 spicesCrocin
The water-soluble pigment of saffron — the rare exception to the rule that spice colourants live in fat, and the reason saffron is steeped in liquid rather than fried.
1 spiceRegulated
Other
Glycyrrhizin
The sweet compound of liquorice root — many times sweeter than sugar, chemically unrelated to anise despite tasting of it, and the one compound here whose everyday consumption carries a documented physiological effect.
1 spiceCitric acid
The sharp, clean sourness of citrus and of most dried souring spices — the acid that tastes immediately of sourness and then gets out of the way.
8 spicesMalic acid
The rounder, slower sourness of apples and stone fruit — the acid that makes a souring spice taste fruity rather than merely sour.
7 spicesBixin
The orange-red carotenoid of annatto, and one of the oldest food colourants still in industrial use — the reason a cheddar is orange and a Yucatecan pork is brick red.
1 spice3-n-Butylphthalide
The compound that makes celery taste of celery — and the reason lovage, celery seed and celeriac all taste of the same thing without being the same plant.
2 spices(E)-2-Decenal
The long-chain aldehyde behind fresh coriander leaf — and behind the fact that a minority of people taste it as soap rather than as citrus.
2 spicesPicrocrocin
The bitter compound of saffron, and the precursor of its aroma: during drying picrocrocin breaks down to release safranal, so the bitterness and the smell of saffron are two stages of one molecule.
1 spice3-Methylindole
The faecal, pig-manure smell found in badly processed white pepper — not a compound of the pepper berry but a product of the retting step in which the skin is rotted off.
1 spice2,5-Dimethylpyrazine
One of the pyrazines behind roasted and nutty notes, named rather than left inside the word “pyrazines”: it forms when nigella, sesame or poppy seed is roasted, and it turns up in some shrimp pastes, where fermentation, sun-drying or both may be what makes it.
6 spices
7 more compounds have a page and are left off this list, because the spice profile already says everything the page does. Search still finds them.