Curcuma kuchoor Royle Curcuma caesia, black turmeric or black zedoary, is a perennial herb with bluish-black rhizomes[2] that is native to northeast India.

The cauldron is covered with a lid, and the rhizomes are boiled for about 30 minutes until foam oozes out with a strong odour.

The rhizomes are taken out when the water is reduced to one-third of the original and they are soft and their inner portion has turned from blue to dark or pale brown.

The research on the volatile rhizomes oil of Curcuma caesia resulted in the identification of 30 components, representing 97% of the oil, with camphor (28%), ar-turmerone (12%), (Z)-ocimene (8%), ar-curcumene (7%), 1,8-cineole (5%), elemene (5%), borneol (4%), bornyl acetate (3%) and curcumene (3%) as the major constituents.

[citation needed] Other research demonstrated diphenylalkanoids, allylbenzene derivatives, terpenoids, flavonoids, steroids, and alkaloids as major constituents.