Choya Nakh

An operculum is a corneous or calcareous structure like a trapdoor that exists in many, but not all, groups of sea snails and freshwater snails. It serves as a sort of trapdoor that closes the aperture of the shell when the soft parts of the animal are retracted. The most common kind is made of a thin to rather thick corneous protein material that is yellow to brownish in color. The opercula of neogastropods are made of a strong protein similar to the keratin of fingernails.

Chemical analysis of opercula smoke revealed aromatic phenols, which act as fragrance stabilisers. Gas chromatography-mass spectrometry revealed a predominance of aromatic compounds in the operculum smoke. Cresol and phenol were consistently present as major constituents, making up 20-40% of the smoke extracts. Simple phenols like cresol could contribute to the musty, leathery note of both castoreum and operculum smoke. Burnt on its own, good-quality operculum reportedly smells of castoreum or other animal musks, while poorer quality smells of burnt hair. Pyridine was detected only in the smoke of untreated opercula, where it was a dominant compound (over 30%).

Unguis odoratus is a Latin term for a traditional incense ingredient used in many cultures and derived from opercula of certain gastropods. Operculum powder is an important ingredient in Chinese and Japanese incense making. The opercula are traditionally treated with vinegar, alcohol and water in order to remove any fishy smell. Neogastropod opercula are still used today in the incense manufacturing industries of India. Murex opercula are still commonly used in traditional North African and Middle Eastern bakhoor.

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Related: Amberwood · Andiroba · Bakhoor · Balsamic Notes · Benzoin Resinoid · Benzyl Benzoate · Benzyl Salicylate · Birch Tar