Curcumin
Also written curcuminoids, curcumin (curcuminoid), curcuminoid
Quick answer
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.
What it does
Curcumin is responsible for turmeric’s colour and for a good part of its bitterness; it contributes almost nothing to the aroma, which comes from a separate volatile fraction dominated by turmerone. That split is why turmeric behaves as it does in a dish — the colour and the bitterness arrive together and stay, while the earthy, faintly gingery smell fades. It is an intensely strong colourant, staining plastic, worktops and fingers at concentrations far below those needed to flavour anything, which is a practical fact about cooking with it and the reason it is used industrially as a food colour.
How it behaves when cooked
Four properties of the molecule, and what they mean at the stove.
- Volatility
- low
- Fat solubility
- moderate
- Water solubility
- low
- Heat stability
- moderate
Curcumin is poorly soluble in water and much better in fat, which is the reason every tradition that uses turmeric seriously cooks it in oil at the start of the dish rather than stirring it into liquid. Turmeric added to a watery stew stays as suspended particles and tastes raw and chalky; the same turmeric bloomed in hot fat for thirty seconds disperses, loses its rawness and colours the whole dish evenly. It needs that heat — raw turmeric powder has a distinctly unpleasant dusty bitterness that cooking removes — but not much of it, since prolonged high heat degrades the pigment and turns a bright yellow dish brownish. It is also markedly sensitive to light and mildly pH-responsive, shifting towards red in alkaline conditions, which occasionally surprises people baking with it and bicarbonate of soda together.
Spices that carry it
Recorded on the compound rather than on each spice, so the two cannot disagree.
- TurmericPrincipal component
Not to be confused with
Compounds a reader is likely to take for this one, and why they differ.
Turmerone
The volatile fraction that supplies turmeric’s aroma. Curcumin supplies colour and bitterness and no smell, which is why the health literature about curcumin and the culinary experience of turmeric are largely about different compounds in the same root.
Capsanthin
The other great spice colourant. Capsanthin is red and fat-soluble; curcumin is yellow and barely soluble in anything. Substituting turmeric for paprika to get colour gives the wrong colour and the wrong solubility behaviour at once.
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.
Almost the entire clinical literature concerns purified curcuminoids at doses formulated for absorption, frequently with a bioavailability enhancer, at exposures nobody reaches by eating turmeric — curcumin is absorbed poorly enough from food that the gap is not a matter of degree. Reported harms, including liver injury, attach to those concentrated preparations. The turmeric profile records what the evidence supports and what it does not, with the exposure stated on every finding; this note exists so that a reader arriving at the compound does not read the supplement literature as a fact about their curry.
Questions this page answers
- what is curcumin
- what does curcumin do
- what is curcuminoids
- what is curcuminoid