Coumarin
Also written coumarin (1,2-benzopyrone), 1,2-benzopyrone
Quick answer
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.
What it does
Coumarin smells of freshly cut hay, sweet almond and vanilla, without being any of them. It is the reason tonka bean is used as a vanilla substitute, the reason blue fenugreek smells sweeter than its seed relative, and part of why cassia reads as rounder and more confectionery than true cinnamon. It has almost no taste of its own; the effect is entirely olfactory and entirely disproportionate to the amount present.
How it behaves when cooked
Four properties of the molecule, and what they mean at the stove.
- Volatility
- moderate
- Fat solubility
- high
- Water solubility
- low
- Heat stability
- high
Coumarin is unusually stable — it survives baking, long cooking and storage largely intact, which is why cassia holds its character in a bun that has been in an oven for half an hour and why tonka bean grated into a cream retains its aroma. It is fat-soluble, so infusing tonka or cassia into cream, butter or custard extracts it efficiently, and this is the standard treatment wherever tonka is legal to use. The stability is also the reason the regulatory question arises at all: unlike most aroma compounds, coumarin does not substantially cook away, so what goes into a food is broadly what comes out of it.
Spices that carry it
Recorded on the compound rather than on each spice, so the two cannot disagree.
- Tonka beanPrincipal component
Present at far higher levels than in any other spice here, and the reason for the United States prohibition on the bean itself.
The whole aroma, and formed on drying or wilting: the living leaf holds it as an odourless bound precursor, which is why fresh woodruff smells of little.
- Blue fenugreekContributing component
- CassiaContributing component
The reason the European tolerable daily intake is discussed in connection with cinnamon at all. Cassia carries substantially more coumarin than Ceylon cinnamon, which carries very little.
- MahlebContributing component
Part of the marzipan-and-hay character that makes mahleb read as almond-adjacent without containing anything almond-related.
- Tej pattaContributing component
Uneven: absent or below quantification in most leaf samples from Himachal Pradesh and Jammu and Kashmir, and present at up to about 1.1 per cent in samples from Uttarakhand. The authors propose it as a marker to screen leaf for.
What cooking and processing were measured to do to it
Findings from studies in which this compound was followed through heat, fat, water, drying or storage. Each belongs to its study and its conditions.
Simmering and boiling · Depends on conditions Cinnamaldehyde, Coumarin, Cinnamic acid, Cinnamyl alcohol, 2-Hydroxycinnamaldehyde
What hot water draws out of cassia bark shifts with the temperature and the time. Between 70 and 95 °C and between 2 and 12 min, hotter and longer extraction raised the coumarin and cinnamyl alcohol content of the extract and lowered its content of cinnamaldehyde, cinnamic acid and 2-hydroxycinnamaldehyde.
Conditions: in water · 70, 75, 80, 85, 90 and 95 °C · 2 to 12 min · Microwave-assisted extraction of Cinnamomum cassia bark with water
A long, hot infusion of cassia is not simply a stronger version of a short one. In this study it held less of the compound that smells of cinnamon and more coumarin.
What this does not show: Read in the abstract only, which gives directions and significance but no concentrations. Microwave-assisted laboratory extraction, and cassia only; it does not speak for Ceylon cinnamon, and it does not say whether the cinnamaldehyde was lost as vapour or chemically changed.
Measured on the spice
Not to be confused with
Compounds a reader is likely to take for this one, and why they differ.
Cinnamaldehyde
The two travel together in cassia and are constantly confused. Cinnamaldehyde is what cinnamon smells of; coumarin is what cassia is limited for. Advice phrased as "cinnamon is restricted" merges them and is wrong twice, since the restriction is on a compound and it distinguishes the two barks.
Warfarin and the anticoagulant coumarins
Coumarin is not an anticoagulant and does not thin blood. The anticoagulant drugs are chemically derived relatives — most famously from spoiled sweet clover — and the persistent claim that eating cassia has an anticoagulant effect confuses a compound with a family of drugs synthesised from it.
Regulatory position
Held on the compound, because the restriction is a fact about the molecule rather than about any one spice.
European Union
limitedEFSA scientific opinion on coumarin (2008); Regulation (EC) No 1334/2008
A tolerable daily intake for coumarin has been established, and maximum levels are set for certain foods. Cassia is a significant dietary source and Ceylon cinnamon is not, which is the practical distinction for anyone consuming cinnamon in quantity daily rather than as an occasional seasoning.
United States
prohibited21 CFR 189.130
Tonka beans and tonka bean extracts are prohibited from use in food in the United States on account of their coumarin content. This is a prohibition on the ingredient rather than a limit on the compound, and it is a different regulatory approach from the European one — the two must not be reported as a single rule.
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.
The established concern is liver effects with sustained high intake, which is why the European position is a daily intake figure rather than a warning about a meal. It becomes practically relevant to people taking cassia cinnamon in supplement quantities every day, and it is essentially irrelevant to seasoning food occasionally. The cassia profile records the distinction between the two barks, which is the actionable part; the tonka bean profile records the United States prohibition.
Questions this page answers
- what is coumarin
- what does coumarin do
- which spices contain coumarin
- what is 1,2-benzopyrone