Capsaicin
Also written capsaicinoids, capsaicin and dihydrocapsaicin, dihydrocapsaicin, capsaicinoid
Quick answer
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 is stable, and nothing a kitchen does destroys it.
What it does
Capsaicin produces no taste and no smell. It stimulates the same nerve endings that report physical heat and abrasion, so the brain receives a signal indistinguishable from a burn — which is why the response is sweating, tears and a raised pulse rather than anything a taste receptor would produce. The sensation builds over roughly twenty seconds, peaks late, and fades slowly, and it accumulates across mouthfuls rather than resetting between them. Chillies also carry dihydrocapsaicin and several minor congeners in varying proportion, and the differing balance is part of why two chillies of similar measured strength can feel like a front-of-mouth sting and a slow throat heat respectively.
How it works
The physiological account, where one is established.
Capsaicin binds a receptor on sensory nerve fibres whose ordinary job is to detect noxious heat, and opens it at body temperature. The receptor is not a taste receptor and is not confined to the tongue: it is present wherever those nerve endings are, which is why capsaicin stings eyes and broken skin, and why cutting chillies without gloves has consequences hours later. Repeated exposure desensitises those endings, which is the basis both of acquired tolerance and of the topical pain preparations that use capsaicin deliberately.
How it behaves when cooked
Four properties of the molecule, and what they mean at the stove.
- Volatility
- low
- Fat solubility
- high
- Water solubility
- low
- Heat stability
- high
Every practical rule about chilli follows from these four properties. Because capsaicin is not volatile, it does not cook off, does not fade in storage, and is not lost from a pre-ground chilli the way aroma is — which is why chilli powder keeps its heat long after it has lost its fruit, and why whole-versus-ground matters far less for heat than for flavour. Because it is fat-soluble and barely water-soluble, water and beer move it around the mouth rather than removing it, while dairy, oil and coconut milk genuinely carry it away; the same solubility is why frying chilli in oil distributes heat evenly through a dish and why simmering it in a watery broth leaves the heat concentrated in the pieces. Because it is heat-stable, a dish cannot be made milder by cooking it longer — it can only be diluted, fattened or acidified.
Spices that carry it
Recorded on the compound rather than on each spice, so the two cannot disagree.
- Chile de árbolPrincipal component
- Bird's eye chilliPrincipal component
- Calabrian chilliPrincipal component
- Carolina ReaperPrincipal component
- Cayenne pepperPrincipal component
- Chilli flakesPrincipal component
- ChipotlePrincipal component
- Ghost pepperPrincipal component
- HabaneroPrincipal component
- JalapeñoPrincipal component
- RocotoPrincipal component
Unusually, distributed through the thick flesh as well as the ribs, so deveining helps less here than in a thin-walled chilli and there is a great deal more flesh to deliver it.
- Scotch bonnetPrincipal component
- SerranoPrincipal component
- Ají amarilloMajor component
Concentrated in the placental ribs rather than the flesh, which is why the Peruvian practice of deveining and blanching drops the heat so far — and why the pod Scoville figure does not describe the dish.
- Aleppo pepperMajor component
- Chilli powderMajor component
- Piment d'EspeletteMajor component
- GochugaruMajor component
- Urfa biberMajor component
- AnchoContributing component
- CascabelContributing component
- GuajilloContributing component
- Kashmiri chilliContributing component
Deliberately low: the variety is grown and selected for colour rather than heat, which is the entire reason it is used by the tablespoon where a hotter chilli would be used by the pinch.
- MulatoContributing component
- PasillaContributing component
- PoblanoContributing component
- PaprikaPresent in small amounts
Sweet paprika is made from cultivars bred down to almost no capsaicin. Hot paprika is the same species with the capsaicin left in, which is why the two are not interchangeable in either direction.
Not to be confused with
Compounds a reader is likely to take for this one, and why they differ.
Piperine
Black pepper is pungent through piperine, which is a different molecule acting on the same nerve population with roughly a hundredth of the potency. Quoting a Scoville figure for black pepper treats the two as one scale, which is why this dataset records the pungency scale explicitly on every profile.
Capsanthin
The red pigment of the same fruit, and a completely separate compound. A chilli can be intensely red and not hot, or pale and ferocious; colour and heat are bred independently.
Safety
What the concern is. The dose, the population and the evidence level live on the spice profiles, which is where a reader with that question actually arrives.
Capsaicin is an irritant rather than a toxin at culinary exposures: the consequences of a large dose are pain, sweating and gastrointestinal upset rather than injury. The exposures that matter are the non-culinary ones — contact with eyes and broken skin when handling chillies, and concentrated extracts, which are a different proposition from the fruit. Individual tolerance varies enormously and is partly acquired.
Questions this page answers
- what is capsaicin
- what does capsaicin do
- which spices contain capsaicin
- what is capsaicinoids
- what is dihydrocapsaicin