The Asian plant Curcuma longa, whose dried, ground rhizomes are the spice turmeric. Its deep yellow colour comes from the curcuminoids — curcumin, desmethoxycurcumin, and bisdesmethoxycurcumin — and it serves as a natural colorant — tinting mustard, pickles and other spicy condiments, curry seasonings, and fats and oils. Its predominant flavour compound, turmerone, gives an earthy, faintly bitter character. Quality vigilance matters: turmeric is sometimes adulterated with synthetic dyes such as metanil yellow or even lead chromate, making authenticity testing important for this high-value spice.