Curcumin
The yellow pigment of turmeric, a dye and food colourant, soluble in oil but not in water.
Also: turmeric pigment, curcuminoid, E100, yellow pigment
Curcumin is the main curcuminoid in turmeric, making up roughly two to five percent of the dried rhizome. It gives the golden-orange colour and a slightly bitter note. It is registered as food additive E100. Curcumin is poorly soluble in water but dissolves in fat and alcohol, which is why turmeric is fried in oil in many recipes, and why spilled curry stains plastic. In alkaline conditions it turns red, as seen when turmeric meets lime in the kumkum of Hindu ritual. Scientists study curcumin extensively. Claims about health effects are matters for medical research, and traditions of using turmeric remain traditions.